Cummins ISL-G Fuel Systems Level One

Home , Mass flow sensor, Throttle position sensor

Technical Resource Guide Doing what matters for jobs and the economy with funding provided by the California Energy Commission (senate bill AB118) through a partnership with the California Community Colleges, Ofﬁ ce of Workforce Development, Advanced Transportation and Renewable Energy sector.

Project Director/Editor Cal Macy

Development team of Subject Matter Experts Cal Macy Bob Vannix Rich Mensel Pete Sparks

Photography Cal Macy Bob Vannix

Created by: Long Beach City College Advanced Transportation Technology Center 1305 E. Paciﬁ c Coast Highway Long Beach, CA 90806 562-938-3067 http://www.lbcc.edu/attc/ This material is based upon work supported by the [email protected] California Energy Commission under Grant No. 12-041-008

Revision 1 ISL-G Fuel Systems October 1, 2014 COURSE INTRODUCTION

Course Title Reference Material installed on technician-provided USB drive upon completion of levels I and II. Cummins ISL-G Level I Prerequisites Course Length Familiarity with Multi-meters, Electrical I or 16 hours CNG courses.

Course Description Objectives This course is designed to give technicians the hands- Upon completion of the course, students will be able to: on skills needed to diagnose and repair the 8.9L ▪▪ Analyze Mass Air Flow Fuel Management Systems Cummins ISL-G CNG Fuel System. The course in- ▪▪ Identify and evaluate the following parameters with a cludes discussion of: DVOM ▪▪ Computerized engine management system ▪▪ Temperature Sensors operation ▪▪ Pressure Sensors ▪▪ Sensors ▪▪ Position Sensors ▪▪ Actuators ▪▪ Voltage Producing Sensors ▪▪ Pin-out voltage values ▪▪ Mass Gas and Air Flow Sensors ▪▪ Cummins Electronic Service Tools ▪▪ Set up INSITE™ to compare readings on parameters It is intended to raise the reliability of the industry and the confidence of the general public in understanding the characteristics, safe handling and working around Competence LNG storage systems. Competence will be measured by both lab Course Benefits demonstration, pre and post tests. Students receive a wealth of experience working on the system and understanding where everything is located and how it works. This class is a must for technicians involved with diagnosis and repair of CNG engine management and fuel delivery systems. Students will learn the proper and safe methods of working with the high-pressure CNG fuel systems using DVOMs and the laptop diagnostic software specific to the Cummins controllers.

ISL-G Fuel Systems 1 Course Introduction

Important Agenda The Material presented here is intended for ▪▪ Component Identification and Location instructional purposes only. Please be sure to follow ▪▪ Taking Resistance and Voltage Measurements manufacturer’s latest bulletins and procedures as the ultimate source. ▪▪ Temperature Sensors

▪▪ Cummins Diagnostic Tools

▪▪ INSITE™ Introduction

▪▪ Pressure Sensors

▪▪ Position Sensors

▪▪ Voltage Producing Sensors

▪▪ Mass Gas and Air Flow Sensors

▪▪ Actuators, Solenoids, Switches and Miscellaneous Signals

2 ISL-G Fuel Systems Course Introduction

Pretest ISL-G Fuel Systems

1. What is the function of temperature sensors? a. Equates a resistance to a temperature b. Equates a temperature to a resistance c. Equates a current to a resistance d. Equates a voltage to a temperature

2. What is the function of pressure sensors? a. Equates a pressure to a resistance b. Equates a current to a pressure c. Equates a pressure to a voltage d. Equates a voltage to a pressure

3. What sensing device does the ECM look at to control fuel delivery? a. Engine Coolant Temperature Sensor / Pressure Sensor

b. O 2 Sensor c. Engine Manifold Pressure Sensor d. Engine Manifold Temperature Sensor

4. What is closed-loop? a. ECM gets the air fuel mixture data from the Exhaust Temperature Sensor b. ECM gets the air fuel mixture data from the Engine Coolant Sensor c. ECM gets the air fuel mixture data from the Engine Manifold Pressure Sensor

d. ECM gets the air fuel mixture requirements from the O2 Sensor

5. What sensor acts as a choke for fuel enrichment? a. Turbine Temperature Sensor b. Intake Manifold Pressure Sensor c. Engine Coolant Temperature Sensor d. EGR Temperature Sensor

6. What is the purpose of the Knock Sensors? a. Sense for engine detonation and advances timing b. Sense for engine detonation and retards timing c. Sense for engine detonation and lean out the fuel mixture d. Sense for engine detonation and increase engine load

ISL-G Fuel Systems 3 Table of Contents

A. Introduction ▪▪ Pretest

1. Theory of Operation ▪▪ Mass Air Flow Systems ▪▪ Cummins Powertrain Management ▪▪ Inputs: Sensors ▪▪ Review Questions ▪▪ Activity 1.1

2. Inputs ▪▪ Temperature Sensors ▪▪ Testing Temperature Sensors ▪▪ Engine Coolant Temperature Sensor ▪▪ Intake Manifold Pressure/Temperature Sensor ▪▪ Turbocharger/Compressor Inlet Humidity/Temp Sensor ▪▪ Turbine Inlet Temperature Sensor ▪▪ EGR Temperature Sensor ▪▪ Fuel Outlet Pressure/Temperature Sensor ▪▪ Catalyst Temperature Sensor ▪▪ Mass Air Flow Temperature Sensor ▪▪ Review Questions ▪▪ Activity 1.2 ▪▪ Pressure Sensors ▪▪ Intake Manifold Pressure/Temperature Sensor ▪▪ Atmospheric Pressure Sensors ▪▪ Intake Manifold Pressure/Temperature Sensor ▪▪ EGR Differential Pressure Sensor ▪▪ Mixer Inlet Pressure Sensor ▪▪ Fuel Inlet Pressure Sensor ▪▪ Fuel Outlet Pressure/Temperature Sensor ▪▪ Engine Oil Pressure Sensor ▪▪ Review Questions ▪▪ Activity 1.3 ▪▪ Speed Sensors ▪▪ Speed Sensor Types ▪▪ Camshaft Speed/Position Sensor (EPS) ▪▪ Crankshaft Speed/Position Sensor (ESS) ▪▪ Vehicle Speed Sensors ▪▪ Position Sensors ▪▪ Throttle Plate Position Sensors 1 and 2 ▪▪ Accelerator Pedal Sensors

4 ISL-G Fuel Systems ▪▪ Remote Accelerator Pedal Assembly ▪▪ EGR Position Sensors ▪▪ Review Questions ▪▪ Activity 1.4 ▪▪ Signal Producing Sensors ▪▪ Catalyst Inlet Oxygen Sensor ▪▪ Catalyst Outlet Oxygen Sensor ▪▪ Testing Heated Oxygen Sensors ▪▪ Signal Producing Sensors ▪▪ Combustion Knock Sensors 1 and 2 ▪▪ Combustion Knock Control Systems ▪▪ Review Questions ▪▪ Activity 1.5 ▪▪ Mass Sensing ▪▪ Mass Gas Sensor ▪▪ Mass Air Flow Sensor ▪▪ Review Questions ▪▪ Activity 1.6 ▪▪ Turbocharger Compressor Inlet Humidity Sensor ▪▪ Coolant Level Sensor ▪▪ ICM Spark Voltage and Misfire Signals ▪▪ CAN, J1939 and J1587 Data Bus ▪▪ Switched ECM Inputs

3. Outputs ▪▪ Outputs, Actuators, Solenoids and Signals ▪▪ Fuel Control Valve ▪▪ Wastegate Control Valve ▪▪ Activity 1.7 ▪▪ Throttle Actuator ▪▪ Fuel Shut-Off Valve ▪▪ Activity 1.8 ▪▪ Electronic EGR Valve ▪▪ Warning and Indicator Lamps ▪▪ Control and Data Signals ▪▪ Ignition Control Module ▪▪ Coil Over Plus Ignition ▪▪ Review Questions

Test CNG Safety Considerations References

ISL-G Fuel Systems 5 Module One 1

6 ISL-G Fuel Systems Theory of Operation

content. The second O sensor, referred to as the ISL-G Theory of Operation 2 Post-Cat HO2S, is located after the output of the The ISL-G system uses a mass airflow and mass gas catalytic converter. Its only function is to monitor the measurements to determine the correct fuel delivery condition of the catalytic converter. It is not used to based upon the engine operating conditions that determine the air-fuel mixture. are present. The airflow measurement is used to The first O sensor’s output is used by the ECM to precisely mix the correct amount of fuel delivery with 2 the metered air entering the engine. A fuel control verify that the fuel control valve position and throttle solenoid is used as an injector to meter fuel delivery plate actuator position are providing the desired exhaust gas condition. If the oxygen content of the with an O2 sensor. This allows the ECM to adjust fuel trim to maintain the most ideal ratio for the operating exhaust indicates a mixture that is rich or lean, the O sensor input to the ECM takes priority over the mode of the engine. An ideal ratio, switching evenly 2 control valve. The second O sensor’s output is between lean and rich, called “stoichiometery” is 2 needed for proper 3-way catalyst operation. used by the ECM to verify the catalyst is operating properly by measuring how effectively it’s storing The control system for this engine is a closed-loop and releasing oxygen. control system. The CM2180A ECM determines the The ECM will use the O sensor information to adjust amount of fuel being delivered by the fuel control 2 valve. It also controls the throttle plate position and the fuel control valve and throttle plate actuator fuel control valve open time to provide the correct positions and provide proper fuel delivery. This air/fuel ratio based upon driver and vehicle demands. compensation deviation commanded by the ECM can In addition, the ECM monitors use the gas mass flow be monitored using INSITE™. If the compensation sensor to compare actual fuel flow to commanded deviation exceeds set limits, the system reverts to fuel flow to compensate for errors. open-loop operation.

The ECM uses preprogrammed look-up table parameters to meet various conditions to satisfy engine requirements when the engine is in open-loop (engine warming up or faults codes are set), and relies on the pre-cat O2 sensor to provide the air-fuel mixture update information when the engine is in closed-loop mode. Each time the engine is started it is in open-loop mode for approximately 1½ to 2 minutes before going into closed-loop mode.

The engine uses a closed-loop control system for Pre-Catalyst Oxygen Sensor its operation. There are two O2 sensors on this engine. The pre-cat oxygen sensor is located just after the turbocharger and before the 3-way catalytic converter. This O2 sensor is used to notify the ECM of the current air-fuel mixture by its oxygen

ISL-G Fuel Systems 7 Module One

The industry utilizes two basic fuel systems, speed Cummins Powertrain Management density and mass airflow. Speed density reacts to changes in manifold absolute pressure. Mass airflow Computers only react where they have been reacts to volume of air entering the engine. Cummins programmed to do so. To operate properly, the mass airflow fuel management uses features from computer must receive a clean steady power supply both systems with the addition of two pressure and have a proper ground. The ECM receives input sensors and a gas mass flow sensor. The mass airflow from sensors and switches. The inputs are processed sensor measures air volume entering the engine. This and compared to a set of programmable calibrations input, along with other sensor inputs, calculates and and instructions. The ECM controls driver circuits monitors the natural gas delivered to the engine. (located inside the ECM) for various outputs, which are usually electro-magnetic components. It is critical the inputs are accurate or resulting outputs will affect driveability.

Inputs: Sensors Inputs to the computer are sensors and signals that tell of changing engine conditions. Inputs are used to monitor parameters needed to keep the engine operating in stoichiometry. Sensors are categorized by their common operational characteristics, although 2. Post-Catalyst Oxygen Sensor they are sensing different parameters The range of sensors may be identical while values Mass Air Flow (MAF) Systems sensed may vary. Air, coolant and oil temperatures are similar on cold engine temperature, but vary Mass Air Flow (MAF) systems use the following greatly when warm. Understanding the relationships parameters as a basic method to calculate and and commonality of the components de-mystifies determine fuel delivery and engine timing: ECM inputs. ▪▪ RPM ▪▪ Mass (Volume) Air Flow ▪▪ Air Temperature = Calculated Volumetric Efficiency ▪▪ Base ignition timing = IMP X EPS ▪▪ Engine Parameters ▪▪ EP x VE x MAF/ AT

8 ISL-G Fuel Systems Theory of Operation

Review Questions What metering devices does the ECM look at to control fuel delivery?

What is closed versus open-loop?

What does TWC mean and what has to happen for it to work correctly?

ISL-G Fuel Systems 9 Module One

Activity 1.1: ISL-G Component Orientation

Locate these components on the engine and place the number or letter of the item in the space provided.

TEMPERATURE SENSORS: 1. Coolant Temperature Sensor ______

2. Intake Manifold Pressure/Temperature Sensor ______

3. EGR Temperature Sensor ______

4. Catalyst Temperature Sensor ______

5. Turbine Inlet Temperature Sensor ______

6. Turbocharger Compressor Inlet Humidity/Temperature Sensor ______

7. Fuel Outlet Pressure/Temperature Sensor (secondary) ______

PRESSURE SENSORS: 8. Fuel Inlet Pressure Sensor (primary) ______

9. Intake Manifold Pressure/Temperature Sensor ______

10. EGR Pressure Sensor ______

11. Mixer Inlet Pressure Sensor (boost sensor) ______

12. Fuel Outlet Pressure/Temperature Sensor (secondary) ______

13. Oil Pressure Sensor ______

14. Compressor Inlet Pressure Sensor ______

SIGNAL PRODUCING SENSORS: 15. Catalyst Inlet Heated Oxygen Sensor ______

16. Catalyst Outlet Heated Oxygen Sensor ______

17. Knock Sensors (front 1,2,3 – rear 4,5,6) ___--___

10 ISL-G Fuel Systems Theory of Operation

POSITION SENSORS: 18. Throttle Position Sensor ______

19. Pedal Position Sensors (APP1 and APP2) ______

20. EGR Position Sensors 1, 2, 3 ______

21. Camshaft Speed/Position (timing) ______

22. Crankshaft Speed/Position (speed) ______

MASS SENSING: 26. Mass Gas Flow Sensor ______

27. Mass Air Flow Sensor ______

OUTPUTS and ACTUATORS: 28. Fuel Control Valve ______

29. Wastegate Control Valve ______

30. Throttle Plate Actuator ______

31. Fuel Shutoff Valve ______

32. Ignition Control Module Timing ______

33. Ignition Control Module Reference ______

34. EGR Valve ______

35. Data Link (Communication) ______

OTHER SENSORS: 36. Coolant Level Sensor ______

37. Turbocharger Compressor Intake Humidity/Temperature Sensor ______

OTHER DEVICES: 38. ECM ______

ISL-G Fuel Systems 11 Module Two 2

12 ISL-G Fuel Systems Inputs

Temperature Sensors acting as a load. Kirchoff’s Law of voltage drops is used as a voltage divider circuit using an internal Temperature sensors are used to measure temperature fixed resistor inside the ECM. The voltage drop across of gas, coolant, engine and intake charge temperatures the thermistor relates to the temperature measured. (as examples). They are thermistor that supply a According to Kirchoff’s Law the sum of all loads will 5-volt reference and ground (return) through the equal the source voltage. When resistance changes ECM. A thermistor is an electrical device that changes across the thermistor (due to temperature changing), resistance as temperature changes. Most thermistors voltage dropped across each resistor changes. The use the same resistance ranges; however, items voltage drop across the thermistor (5 volt-signal and monitored will reach different operating temperatures. signal return) is what the ECM looks at to correspond They will all look similar at cold startup then change. to actual temperature. As an example, coolant will measure hotter than air temperature. Kirchoff’s law

There are two types of thermistors, Negative 1. 100% of supplied voltage consumed by circuit. Temperature Coefficient (NTC) and Positive 2. The voltage drop across the fixed resistor will be Temperature Coefficient (PTC). On NTC thermistors, proportional to the resistance value of the thermistor. resistance is high when cold and low when hot. NTC thermistors are the most accurate and commonly used An open circuit would have zero current flow and the in automotive applications. On PTC thermistors, voltage at the signal would be 5V. resistance is low when cold and high when hot. For either type of thermistor, resistance change is linear. Vd=It x R(x) To have a voltage change in the temperature circuit, a fixed resistor is added in series with the thermistor. The A shorted circuit on the supply side of the thermistor resistor is actually inside the ECM. Two resistors in would be 0 volts at the signal as all the voltage series make a voltage divider circuit with each resistor would be consumed by the fixed resistor.

Testing Temperature Sensors There are two ways to test thermistors; by measuring resistance and measuring voltage.

When measuring voltage, the thermistor is left connected in the circuit and the circuit is powered up. The voltage drop is measured across the 5V signal and signal return pins by back probing the thermistor connector. We then can compare this voltage drop with known good values for the actual temperature of ECM Circuit the sensor.

ISL-G Fuel Systems 13 Module Two

Engine Coolant Temperature Sensor The Engine Coolant Temperature (ECT) Sensor is always threaded into the coolant system so that the sensor tip is in direct contact with the engine coolant. The purpose is to sense the temperature of the coolant. This acts as a choke for fuel enrichment and timing increases when the engine is cold.

The coolant temperature sensor input to the ECM is used for engine protection, ignition timing, and fueling control. When cold, the system adds fuel, advances timing and increases idle speed. Once it is Measuring Resistance warmed up and no longer providing a choke circuit Another way to test thermistors is to measure the sensor monitors for overheating. If the coolant resistance. In order to do this it will need to be temperature is too high, engine de-rate will occur and disconnected from the circuit for two reasons. possibly lead to engine shutdown.

1. There can be no voltage to the device as the meter A thermistor used as ECT sensor is a two-wire will provide its own power. sensor with a signal and a return. Thermistors change resistance as their temperature changes which 2. We only want to measure the resistance of the changes, the voltage drop across the fixed resistor thermistor device. After being disconnected, you inside the ECM. It is checked by comparing the would measure the resistance at the signal and return temperature of the sensor with voltage and resistance pins on the thermistor. readings.

If it fails, it can cause a hard-start or no-start condition in a cold soaked engine and a rich-flooding condition when warm. The ECM will have a fail-safe backup strategy in case of sensor failure to reduce these problems.

ECT Mounted in Coolant Jacket

Coolant Temperature Sensor ECT Connector

14 ISL-G Fuel Systems Inputs

has the 5-volt reference, a pressure signal input and temperature signal output and returns. There are separate circuits for the pressure signal and temperature signal. The temperature signal is a thermistor that should be measured between the temperature signal and the common signal return. The pressure signal is a transducer that should be measured between the pressure signal and ground. Verifying the readings with known good values will Intake Manifold Pressure/Temperature Sensor determine if the components are accurate.

Turbocharger/Compressor Inlet Humidity/Temperature Sensor The turbocharger compressor inlet housing connects the air cleaner to the turbocharger. This housing contains the Inlet Air Temperature and Humidity dual sensor. This provides air temperature and humidity to the ECM which uses the information to IMPT Senses Pressure and Temperature help in determining fuel trim and the proper ignition timing. Humidity adds water that contains oxygen, which affects stoichiometery. This will be covered in Intake Manifold Pressure/ a later section. Temperature Sensor The Intake Manifold Pressure Sensor/Temperature Sensor, a combination sensor, is located at the rear of the intake manifold. Its job is to sense the charge air temperature and pressure in the manifold, which is used to determine engine timing and boost requirements. TCIH/Temp Sensor

The ECM uses the intake manifold pressure information to control engine fueling and boost. The intake manifold temperature information is used for engine overheat protection due to hot intake air. Located in Inlet Housing TCIH/Temp Sensor The combination Intake Manifold Pressure/ Monitors Intake Air Temperature Sensor contains a 4-wire plug which

ISL-G Fuel Systems 15 Module OneTwo

The temperature portion of the inlet humidity/ across the signal and return and compare the temperature sensor is a thermistor that monitors the resistance with known good values for the given temperature of the ambient air entering the engine. temperature of this sensor. When the air is cold and dense, it contains more oxygen than hot air so the fuel delivery and timing must be adjusted to maintain a stoichiometric ratio. EGR Temperature Sensor Testing the thermistor circuit can be accomplished A temperature sensor is a thermistor located in the using the temperature signal and common return EGR crossover tube to sense the temperature of the connections by measuring resistance or voltage and exhaust entering the EGR valve. comparing them to the actual temperature and known good values from the specifications or a similar sensor. NOTE: This sensor can become coated and have false readings to the ECM if the EGR cooler leaks, allowing coolant to flow into the Turbine Inlet Temperature Sensor exhaust chamber. The EGR temperature sensor is used by the ECM, in The turbine inlet temperature sensor is in the path conjunction with the exhaust gas differential pressure where the exhaust enters the turbine. This senses the sensor, to calculate the volume of re-circulated temperature of the exhaust stream. A bi-metallic exhaust gases that enter the intake manifold from the pyrometer-type sensor is utilized as it can handle exhaust gas recirculation valve. It also will de-rate much higher temperatures than a thermistor. It is the engine if the EGR temperature is greater than the used for critical protection preventing turbo and engine protection limits. catalyst overheating.

Pyrometer Temperature Sensor

Excessive exhaust heat is caused by excess fuel and turbo boost. Excessive heat in the exhaust will cause a failure of the catalytic converter as the substrate will melt down EGR Temperature Sensor and blockage will occur. Excessive temperatures may initiate a power de-rating by the ECM. The EGR Temperature Sensor is a two-wire The pyrometer-type temperature sensor has two thermistor sensor. It determines the temperature of wires, signal and return, and works much like a the exhaust gas coming from the exhaust manifold thermistor. To test this sensor, measure the resistance in order to determine the amount of flow necessary.

16 ISL-G Fuel Systems Inputs

Along with this sensor and the delta pressure sensor, recognize. This sensor has also been referred to as the ECM uses this information to determine EGR the secondary and also the fuel outlet pressure/temp flow under load and keep flow to a maximum of 30%. sensor. The sensor has a thermistor in it to measure the temperature of the fuel entering the control valve. The NOTE: When refilling cooling system, always ECM compensates for the density changes in the fuel fill until coolant comes out at bleeder fitting due to the temperature fluctuations. The control valve on top of EGR cooler and/or hose to recovery on-time is adjusted to deliver comparable BTUs of fuel tank at top of radiator. Then, run engine with depending upon its temperature. radiator cap off and heater turned on for 10- 20 minutes, depending on vehicle, to make The fuel temperature is monitored and used for sure cooling system is free of all air. a critical engine protection function. The ECM monitors the fuel temperature and if it exceeds limits, An EGR cooler leak issue requires proper bleeding of can turn on the warning lights and de-rate or even system or damage to turbo may result. shut the engine down, depending upon the severity. DPS ports can fill with water. Blow them out. If the fuel temperature is too low, low power will occur along with icing on the fuel lines and fittings. Refer to Cummins procedures. This is usually a result of a cooling system problem. When the fuel temperature is too high, the engine may detonate and experience low power. In both cases, the ECM may de-rate or shut down the engine with fault codes and warning lamps illuminated.

EGR Temp 2-wire EGR Temperature Connector

Fuel Outlet Pressure/Temperature Sensor The Fuel Outlet Pressure/Temperature sensor is currently referred to as the Fuel Control Valve Intake Pressure/Temperature sensor. Differences in terminology for the same component can exist between publications and versions of software that we need to Fuel Control Valve Intake Press/Temp Sensor

Dual function sensors have multiple circuits within the same connector. This sensor has a separate 5V supply and pressure signal to the ECM along with the 5V voltage supplied on the temperature signal connection through the internal fixed resistor in Fuel Outlet Pressure/ Dual Sensor Connector Temperature Sensor

ISL-G Fuel Systems 17 Module Two the ECM. The temperature sensor has a return to Mass Air Flow Temperature ground through the computer. When checking Sensor the temperature circuit, voltage drop between the temperature signal and signal return are compared The Mass Airflow (MAF) has a separate temperature to graphs and scan tool readings to verify the sensor internally to measure the incoming air validity of the reading. Variations can be caused temperature. Temperature variations affect the by faulty components or connections including the density of the air and oxygen delivered to the computer ground. engine. It is used by the air flow meter in its internal calculations that are sent to the ECM. The airflow temperature sensor reading is used internally by the Catalyst Temperature Sensor mass airflow meter.

The location of this sensor is at the output of the INSITE™ does not show air temperature as a catalytic converter. separate parameter as it is used in the calculations The catalyst temperature is also a bimetallic made by the independent computer circuit in the pyrometer-type temperature sensor. It is a two-wire Mass Air Flow Meter. The sensor can be tested sensor that works much like the thermistors but at manually using a voltmeter on the temperature higher temperatures. Using known good resistances signal and signal return connections to the airflow for given temperatures can be helpful to check meter like the other thermistors. Comparison to calibration. manual pyrometer readings can be used to verify the temperature using resistor charts in the technical This sensor monitors the temperature of the exhaust specifications for sensors with similar values. gas after the two catalysts. If the exhaust gas temperature exceeds the specified setting of 1350 °F (732 °C), the ECM will severely de-rate the engine to keep the high temperature exhaust gas from damaging the catalyst bricks. At 1375 °F (746 °C), engine shutdown will occur.

Catalyst Temperature Sensor

18 ISL-G Fuel Systems Inputs

Review Questions A temperature sensor is what type of device?

What does NTC stand for? Explain the relationship.

What does the ECM have to make a temperature sensor work?

ISL-G Fuel Systems 19 Module Two

Activity 1.2: Cummins Temperature Sensors

Fuel Outlet Pressure/Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infra-red Pyrometer 4. DVOM

Step 1: Using the repair manual, locate the ECM wiring diagram:

FOP/T – 5-volt Reference Wire Terminal ______Pressure Signal Terminal ______Signal Return Wire Terminal ______Temperature Signal Terminal ______

Step 2: a. Back-probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect sensor, record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the Infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart under KOEO g. Record the sensor’s signal voltage from step 2a in the chart under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart under KOEO. i. With KOER, log temperature and voltage readings at 30-second intervals and record in the spaces provided.

20 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 21 Module Two

Activity 1.2: Cummins Temperature Sensors

Turbine Inlet Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infrared Pyrometer 4. DVOM

Step 1: Using the repair manua,l locate the Turbine ITS wiring diagram:

Turbine Inlet Temp Senor 5-volt Reference Wire Terminal ______Sensor Return Wire Terminal ______

Step 2: a. Back-probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect sensor. Record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart under KOEO. g. Record the sensor’s signal voltage from step 2a in the chart under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart below under KOEO. i. With KOER, log temperature and voltage readings at 30-second intervals and record in the spaces provided.

22 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 23 Module Two

Activity 1.2: Cummins Temperature Sensors

Compressor Inlet Humidity and Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infrared Pyrometer 4. DVOM

Step 1: Using the repair, manual locate the ECM wiring diagram:

CIH/T – 5-volt Reference Wire Terminal ______Humidity Signal Terminal ______Sensor Return Wire Terminal ______Temperature Signal Terminal ______

Step 2: a. Back probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect sensor, record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart under KOEO. g. Record the sensor’s signal voltage from step 2a in the chart under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart under KOEO. i. With KOER, log temperature and voltage readings at 30-second intervals and record in the spaces provided.

24 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 25 Module Two

Activity 1.2: Cummins Temperature Sensors

EGR Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infrared Pyrometer 4. DVOM

Step 1: Using the repair, manual locate the EGRT wiring diagram.

EGRT – 5-Volt Reference Wire Terminal ______Sensor Return Wire Terminal ______

Step 2: a. Back-probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect Sensor, record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart under KOEO. g. Record the sensor’s signal voltage from step 2a in the chart under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart under KOEO. i. With KOER log temperature and voltage readings at 30-second intervals and record in the spaces provided.

26 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 27 Module Two

Activity 1.2: Cummins Temperature Sensors

Catalyst Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infra-red Pyrometer 4. DVOM

Step 1: Using the repair manual, locate the CAT TEMP wiring diagram.

Catalyst – 5-volt reference wire terminal ______

Sensor return wire terminal ______

Step 2: a. Back-probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect Sensor, record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart under KOEO. g. Record the sensor’s signal voltage from step 2a in the chart under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart under KOEO i. With KOER, log temperature and voltage readings at 30-second intervals and record in the spaces provided.

28 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 29 Module Two

Activity 1.2: Cummins Temperature Sensors

Engine Coolant Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infrared Pyrometer 4. DVOM

Step 1: Using the repair manual locate the ECM wiring diagram.

ECT – 5-Volt Reference Wire Terminal ______Sensor Return Wire Terminal ______

Step 2: a. Back-probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect Sensor, record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart below under KOEO. g. Record the sensor’s signal voltage from step 2a in the chart below under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart below under KOEO. i. With KOER, log temperature and voltage readings at 30-second intervals and record in the spaces provided below.

30 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 31 Module Two

Activity 1.2: Cummins Temperature Sensors

Intake Manifold Temperature Sensor

Tools and equipment:

1. Cummins Troubleshooting and Repair Manual 2. INSITE™ (optional) 3. Infrared Pyrometer 4. DVOM

Step 1: Using the repair manual locate the IMT wiring diagram

IMT – 5-volt Reference Wire Terminal ______Sensor Return Wire Terminal ______

Step 2: a. Back-probe the sensor’s signal wire with the DVOM and measure sensor’s signal voltage. Voltage ______b. Connect INSITE™ and view parameters for temperature and the associated voltage for sensor. Temperature ______Signal Voltage ______c. Disconnect Sensor, record the resistance across sensor with the DVOM set to measure resistance. Resistance ______d. Compare the temperature and resistance to the Cummins specs. Is it within range? Yes / No e. Measure the temperature with the infrared pyrometer. Temperature ______f. Reconnect sensor and record the pyrometer temperature from Step 2e in the chart under KOEO. g. Record the sensor’s signal voltage from step 2a in the chart under KOEO. h. Record the voltage and temperature from INSITE™ in Step 2b in the chart under KOEO. i. With KOER, log temperature and voltage readings at 30-second intervals and record in the spaces provided.

32 ISL-G Fuel Systems Inputs

KOEO 30 60 90 120 150 180 210 240 270

Pyrometer

DVOM

INSITE™/ TEMP/V

Step 3: Re-measure DVOM resistance with the sensor disconnected. Resistance ______

Step 4: Using INSITE™, record diagnostic codes and temperature readings. Diagnostic Trouble Codes (DTC) ______Temperature reading ______

Step 5: Short the harness connector and record the temperature and diagnostic code from INSITE™. Diagnostic Trouble Code ______Temperature reading ______

ISL-G Fuel Systems 33 Module Two

Pressure Sensors Intake Manifold Pressure/ Temperature Sensor Pressure sensors are transducers that drop a supply voltage based upon the pressure being monitored. The combination Intake Manifold Pressure/Tempera- The input pressure sensors are used to control power ture Sensor has a 4-wire plug which has the 5-volt output and emissions of the engine. reference, a pressure signal input and temperature signal output and returns. There are separate circuits for the pressure signal and temperature signal. Intake Manifold Pressure/ The pressure signal is a transducer that should be Temperature Sensor measured between the pressure signal and ground. Verifying the readings with known good values will The Intake Manifold Pressure/Temperature Sensor, determine if the components are accurate. a combination sensor, is located at the rear of the intake manifold. EGR Differential Pressure Sensor The ECM uses intake manifold pressure to measure the charge air pressure in the manifold to determine The EGR Differential Pres- engine timing and boost requirements. The timing sure Sensor (DPS) is also signal is then sent to the (IM). called the Delta Pressure Sen- sor. It compares the pressure differential between the ex- Atmospheric Pressure Sensors haust manifold and the intake manifold pressures and sends When working with pressure sensors, we need to take EGR DPS a signal, that is the pressure into consideration what pressure is being measured. differential from the two ports. This DPS can become Atmospheric pressure is the pressure around us and damaged if the EGR cooler leaks into the system and is referred to as barometric pressure. It is affected contaminates all components. The severity depends by altitude and weather conditions. The readings at on how bad the cooler is leaking. sea level are reduced by 1”hg (inches of mercury) for every 1000 feet of altitude The exhaust gas recirculation differential pressure sensor is used by the ECM, in conjunction with the ex- Sea level = 29.8“ hg or 14.64 psi haust gas recirculation temperature sensor, to calculate 4.5 psi = 100 kPa“ = 1 BAR @ 32°F the volume of re-circulated exhaust gases that enter the intake manifold from the exhaust gas recirculation Absolute pressure is the pressure without atmospheric valve. This limits EGR gas to a maximum of 30%. pressure’s influence. These gauges would read 14.7 psi lower at sea level. The EGR DPS has a 5-volt reference, pressure signal and signal return.

34 ISL-G Fuel Systems Inputs

Mixer Inlet Presure Sensor The throttle inlet housing connects the air charge cooler to the mixer housing which provides the charged air to the mixer.

Mixer Inlet Pressure Sensor This inlet housing also contains the Mixer Inlet Pressure (Boost) sensor

EGR DPS Location and the MAF Sensor. The Mixer Inlet Pressure The parameters for this sensor are available through (Boost) sensor provides INSITE™ and include: boost pressure informa- Mixer Inlet Pressure tion to the ECM. 1. EGR valve flow compensation - It is the control Connector compensation required to reduce the EGR valve The Mixer Inlet Pressure flow error. (Boost) Sensor measures boost pressure while under load, and atmospheric pressure when not under load. 2. EGR valve flow control state - Indicates to the tool From this, the ECM calculates air density and deter- the state of current control of EGR valve. 0 = control mines the engine’s air mass flow rate, which in turn off, 1 = open-loop control, 2 = closed-loop control. determines the required fuel metering for optimum combustion and influences the advance or retard of 3. EGR valve flow error - Indicates to the tool the dif- ignition timing. ference between EGR flow sensed and commanded.

The Mixer Intake Pressure Boost Sensor is a 3-wire 4. EGR valve position commanded - Indicates to the sensor ,as in all pressure transducers. It has a 5-volt tool whether the EGR valve feature is enabled in the reference, with signal and return lines. When taking ECM. This parameter is not user adjustable. measurements for pressure and comparing to known good values, always use the signal and return connec- 5. EGR valve position measured - Position (percent tions. You will also want to confirm that the sensor open) of the EGR valve after auto zero. has the appropriate 5-volts to operate properly. 6. EGR valve position sensor signal (voltage) - Sensor input voltage detected by ECM.

ISL-G Fuel Systems 35 Module Two

Fuel Inlet Pressure Sensor NOTE: The example of known good values can be used when checking the sensor for The Fuel Inlet Pressure accurate calibration of pressures. Sensor is mounted on the secondary fuel regulator Fuel Outlet Pressure/Temperature housing to measure the Sensor incoming pressure.

Fuel Inlet Pressure Sensor The OEM manufacturer is responsible for providind regulated and filtered natural gas at 120 psi to the engine. This can come from CNG or LNG storage systems, providing the pressure at the required volume is maintained.

To test this pressure sensor, measure voltage at pin B with a DVOM and note changes when fuel pressure varies. Optionally, you can connect a me- chanical gauge or an external pressure transducer The Fuel Outlet Pressure/Temperature Sensor, also for a DVOM to the pressure ports to monitor fuel known as the Control Intake Pressure/Temperature Sensor, measures the pressure of the engine entering pressure. These ports are on the Low-Pressure Fuel the Control Valve. Regulator Assembly. Note that gauge pressure is about 15 psi less than what you see on INSITE™ as The Fuel Outlet Pressure/Temperature or Fuel Con- INSITE™ is showing actual pressure, which most trol Valve Intake Pressure/Temp sensor measures the gauges do not. This gauge is reading the pressure pressure of the fuel entering the control valve. above atmospheric which means the gauge starts at zero, not the 14.7 psi present in the atmosphere. The ECM monitors this pressure for best perfor- mance. Restrictions, such as a contaminated fuel filter, can cause low power while high pressure can cause hard-starting. Oil from a failing CNG compressor at a fueling station can saturate the filter causing pressure and volume loss. Bleeding of contaminates from the filter and replacement should be regular Preventive Maintenance items.

The pressure in the secondary should be maintained at 65-73 psi while under load with unrestricted flow.

Testing the pressure side of the circuit involves measuring the outlet pressure under a load and comparing OEM Supplied Regulator and Filter the voltage signals to a manually installed gauge or

36 ISL-G Fuel Systems Inputs

Review Questions

What is the Primary Pressure?

What is the Secondary Pressure? Oil Pressure Sensor

INSITE™ readings. The readings on the gauge and INSITE™ will vary by 14.7 psi, as the gauge will read in absolute.

Engine Oil Pressure Sensor

The Engine Oil Pressure Sensor is threaded into the side of the block behind the ECM. It senses engine oil pressure for critical engine protection. The oil pressure should read “0” psi with the key on and engine off. A faulty gauge reading can cause problems if the engine pressure is then lost.

The ECM uses input from the oil pressure sensor for engine protection. If the oil pressure is too low, engine de-rate and possible shutdown will occur.

Oil pressure sensors are 3-wire transducer devices that run on 5-volts. Testing the sensor involves verifying the pressure and comparing it to the pressure signal voltage while using the signal return for a ground.

ISL-G Fuel Systems 37 Module Two

Activity 1.3: Cummins Pressure Sensors

Fuel Outlet Pressure/Temp Sensor

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. Tool Set 3. INSITE™ 4. DVOM

Step 1: Using the repair manual, locate the Fuel Outlet Pressure/Temp Sensor wiring diagram.

A. FOP/T Signal Return Wire terminal ______B. FOP Signal Wire terminal ______C. FOP/T 5-volt Reference Wire terminal ______D. FOT Signal Wire terminal ______

Step 2: Locate the FOP/T sensor and identify the wiring harness.

Step 3: If available, connect the test gauge. Connect INSITE™ and view the FOP/T sensor data for voltage and pressure. Back-probe the FOP/T sensor signal wire with the DVOM. With KOEO, record the pressure/voltage readings as specified below. Record the following measurements for KOER as specified below. a. 0” of vacuum (KOEO) INSITE™ _____Volts ______PSI DVOM ______b. Idle (15”of vacuum) c. INSITE™ _____Volts ______PSI DVOM ______d. Stall Test INSITE™ _____Volts ______PSI DVOM ______

38 ISL-G Fuel Systems Inputs

Activity 1.3: Cummins Pressure Sensors

Intake Manifold Pressure/Temp Sensor

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. Tool Set 3. INSITE™ 4. DVOM

Step 1: Using the repair, manual locate the Intake Manifold Pressure/Temp Sensor wiring diagram. A. IMP/T Signal Return Wire terminal ______B. IMP Signal Wire terminal ______C. IMP/T 5-volt Reference Wire terminal ______D. IMT Signal Wire terminal ______

Step 2: Locate the IMP/T sensor and identify the wiring harness.

Step 3: Connect INSITE™ and view the IMP/T sensor data for voltage and pressure. Back-probe the IMP/T sensor signal wire with the DVOM. With KOEO, record the pressure/voltage readings as specified below. Record the following measurements for KOER as specified below. a. 0” of vacuum (KOEO) INSITE™ _____Volts ______InHg DVOM ______b. Idle (15”of vacuum) c. INSITE™ _____Volts ______InHg DVOM ______d. Stall Test INSITE™ _____Volts ______InHg DVOM ______

ISL-G Fuel Systems 39 Module Two

Activity 1.3: Cummins Pressure Sensors

Mixer Inlet (Boost) Pressure Sensor

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. Tool Set 3. INSITE™ 4. DVOM

Step 1: Using the repair manual, locate the Mixer Inlet Absolute Pressure Sensor wiring diagram.

A. MIP Signal Return Wire terminal ______B. MIP Signal Wire terminal ______C. MIP 5-volt Reference Wire terminal ______

Step 2: Locate the MIP sensor and identify the wiring harness.

Step 3: Connect INSITE™ and view the MIP sensor data for voltage and pressure. Back-probe the MIP sensor signal wire with the DVOM. With KOEO, record the pressure/voltage readings as specified below. Record the following measurements for KOER as specified below. a. 0” of vacuum (KOEO) INSITE™ _____Volts ______InHg DVOM ______b. Idle (15”of vacuum) c. INSITE™ _____Volts ______InHg DVOM ______d. Stall Test INSITE™ _____Volts ______InHg DVOM ______

40 ISL-G Fuel Systems Inputs

Activity 1.3: Cummins Pressure Sensors

Fuel Inlet Pressure Sensor

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. Tool Set 3. INSITE™ 4. DVOM

Step 1: Using the repair manual, locate the Fuel Inlet Pressure Sensor wiring diagram.

A. FIPS Signal Return Wire terminal ______B. FIPS Sensor Signal Wire terminal ______C. 5-volt Reference Wire terminal ______

Step 2: Locate the FIPS sensor and identify the wiring harness.

Step 3: If available, connect the test gauge. Connect INSITE™ and view the FIPS sensor data for voltage and pressure. Back-probe the FIPS sensor signal wire with the DVOM. With KOEO, record the pressure/voltage readings as specified below. Crank the engine and record the pressure/voltage readings as specified below. With KOER record the pressure/voltage readings as specified below. a. 0” of vacuum (KOEO) INSITE™ _____Volts ______PSI DVOM ______b. Idle (15”of vacuum) c. INSITE™ _____Volts ______PSI DVOM ______d. Stall Test INSITE™ _____Volts ______PSI DVOM ______

ISL-G Fuel Systems 41 Module Two

Speed Sensors the rear of the camshaft gear. Whenever the cam gear protrusions pass the EPS, the deflection in the sensor Two types of speed sensors are present to sense flux lines generates a digital pulse signal to the ECM. engine and vehicle speed along with cylinder location.

The ECM uses the frequency of the signal resulting Speed Sensor Types from the six evenly-spaced cast protrusions passing A speed sensor senses speed of a rotating shaft and the EPS to calculate engine speed and, with the Intake creates an electrical signal that can be interpreted by Manifold Pressure/Temperature Sensor input, adjusts the ECM. There are two types of speed sensors: the ignition timing. The ECM recognizes the seventh ▪▪ Hall-Effect Sensor (Switch), which produces a signal from the one unevenly spaced protrusion as digital on-off signal that is very precise. Hall- the indicator for the start of a new cycle. Each cycle Effect sensors are 3-wire sensors and are used for begins with cylinder #1 as the next cylinder to fire. crankshaft and camshaft sensing. The ECM uses this signal to generate the spark reference signal for the ICM. ▪▪ Magnetic Reluctance Sensor, which produces an A/C Signal. The camshaft speed sensor is a Hall-Effect type These sensors are usually used to determine vehicle sensor with three wires. speed and as ABS wheel sensors.

When testing the sensor, check the signal return and Camshaft Speed/Position Sensor ground. This will be a digital on-off signal, which can (EPS) be seen with a digital storage oscilloscope, and will increase in frequency on a DVOM as the engine RPM The Engine Camshaft Speed/Position Sensor (EPS) increases. The voltage will remain fairly constant. is mounted on the gear housing. It measures the position of the engine camshaft by the use of a Hall- Effect sensor and seven cast protrusions located on

EPS has Offset Mounts

Camshaft Position Sensor Connector EPS

42 ISL-G Fuel Systems Inputs

Crankshaft Speed/Position When testing the sensor, check the signal return and Sensor (ESS) ground. This will be a digital on-off signal, which can be seen with a digital storage oscilloscope, and Another speed sensor is the engine Crankshaft Speed/ will increase in frequency on a DVOM as the engine Position Sensor (ESS), which is mounted at the rear RPM increases. The voltage will remain fairly of the block to measure crankshaft speed. The ESS constant near 2.5V. measures the position of the engine crank by the use of a Hall-Effect sensor and a tone wheel located on the rear of the crankshaft. Whenever the crankshaft tone-wheel gear protrusions pass the ESS, the deflection in the sensor flux lines generates a digital pulse to the ECM.

Crankshaft Speed Sensor

The information from this sensor is used by the ECM to determine crankshaft rotational speed and Tone Wheel position as a backup to the camshaft sensor. It is the Protrusions tachometer signal used by the computer to recognize the engine is cranking to turn on the fuel solenoids.

The ESS is a Hall-Effect type sensor with three wires. It does not create electricity, just turns a circuit on and off.

ISL-G Fuel Systems 43 Module Two

Vehicle Speed Sensors Position Sensors The Vehicle Speed Sensor (VSS) provides vehicle Position sensors are potentiometers that are used to speed information to the ECM. This sensor generates determine where a moving item is currently located. a signal based on the movement of gear teeth from a There are several potentiometers used to sense throttle gear on the transmission tail shaft. As the gear teeth position and demand, along with EGR movement. pass the sensor, a variable frequency signal is generated. Throttle Plate Position Sensors 1 and 2 The ECM also uses VSS to de-rate and/or cut fuel when customer parameters are set to a certain road speed. This engine runs a “fly by wire” throttle system. The driver signals demand for acceleration to the ECM and the ECM moves the throttle plate as needed. The VSS is a two-wire sensor that is a magnetic Potentiometers are used to see where the throttle plate inductive pickup. It is comprised of a permanent is currently positioned. magnet and a coil. When the tone wheel comes close to the coil during operation, it causes the magnetic field to shift through it, inducing an A/C voltage that changes in frequency.

TPP 1 and 2 Located in Throttle Actuator Assembly Vehicle Speed Sensor The ECM uses the measured position (sensed Position Sensors position) of the throttle plate potentiometer to control fueling and engine speed. There are two sensors (TPP1 and TPP2) and the ECM compares these two signals to ensure they match as a means of safety and redundancy. If they do not match or compare to the command opening, then the system sets a fault and goes into an idle-only mode.

44 ISL-G Fuel Systems Inputs

These potentiometers are 3-wire sensors that run on a common 5-volt reference with a return. The movable arm in the sensor returns a portion of the voltage to the ECM with throttle plate movement. When performing a normal voltage check on TPP1 and TPP2 - you will notice that one sensor’s voltage starts higher and goes up while the other sensors voltage starts lower and goes higher.

Accelerator Pedal Sensors Throttle Actuator These engines use two throttle position sensors mounted on the accelerator pedal to determine throttle demand by the driver. Like the Accelerator plate position, these two sensors are redundant. Earlier Cummins systems used a single throttle position sensor and an idle validation switch. Care must be taken to ensure the correct pedal position Throttle Actuactor APP 1 and 2 on Throttle Pedal sensor is installed. Connector components. This ability will always enable the engine to reach 100 percent commanded position, The dual Hall-Efect accelerator pedal is designed independent of variations in the accelerator pedal for an accelerator pedal sensor that translates a component. Accelerator Pedal Sensor 1 (APS1) and position controlled by the operator, into two analog Accelerator Pedal Sensor 2 (APS2) have different voltage signals, Accelerator Pedal Sensor 1 (APS1) position to voltage transfer functions. This allows the and Accelerator Pedal Sensor 2 (APS2). The ECM ECM accelerator algorithm to perform an integrity processes these signals for verification of the check of the two signals before outputting a final accelerator position. On automotive applications, commanded accelerator value to the rest of the this type of interface requires that the pedal, when system. APS1 has a starting voltage of 1.25 volts and released, returns to the idle position via a return a wide open throttle voltage of 4.20 volts. APS2 has a mechanism in the pedal assembly. starting voltage of 0.56 volts and a wide open throttle voltage of 2.06 volts. Note that both sensors start at The software in the ECM is able to compensate for two different points and rise together to a wide open variations in the voltage output of the accelerator throttle position. A fault code will be generated if any pedal component when the pedal is at the idle of a number of concerns happen: accelerator pedal position. This ability minimizes the dead band of position 2-signal circuit shorted to battery or 5-volt the accelerator pedal near the idle position as the supply, open accelerator pedal return circuit in the accelerator pedal components age or wear and harness or connections, accelerator supply shorted to eliminates noticeable differences due to normal battery, or failed accelerator pedal position sensor. variations between different accelerator pedal

ISL-G Fuel Systems 45 Module Two

Remote Accelerator Pedal ▪▪ Terminal A of the APP is connected to the ECM Assembly ground at terminal 17, and terminal B of the APP provides the position signal return data to the Some vehicles have a remote ECM at terminal 30. throttle pedal assembly located ▪▪ The APP can be pinpoint tested using a DVOM or at the rear of the vehicle to aid an oscilloscope. in remote engine control. For troubleshooting purposes only, ▪▪ The preferred method is to use an oscilloscope and perform a sweep test. The sweep test Remote Accelerator a switch must be thrown on the Pedal Assembly remote unit to change from inside will detect opens, or glitches, that may not be to remote operation. detectable with the DVOM. ▪▪ Normally, the APP will return approximately 10% The remote throttle control is a Hall-Effect switch of the supply voltage at idle, and approximately just like what is in the accelerator pedal. When 90% at wide open throttle. activated, the throttle can be operated manually from ▪▪ As the accelerator pedal is slowly pushed down, the rear. the signal return voltage at terminal B of the sensor will gradually increase from .5V to 4.0V. ▪▪ If the accelerator position voltage is determined to be out of range by the GCM, a code 18 will be set and the engine will idle. ▪▪ The override switch will provide limp-home operation of the system.

EGR Position Sensors There are three EGR motor windings that move to

Remote Pedal Control control the EGR flow. The EGR valve motor has three position sensors inside that confirm the position of the EGR valve motors to the ECM. The ECM switches the control for the main and remote sensors when the interlock switch is on. The EGR valve is controlled by the ECM and ▪▪ The Accelerator Pedal Position (APP) sensor is regulates the amount of re-circulated exhaust gases connected to ECM in this application via a three- that enter the intake manifold based on sensor input of wire connector. motor rod location, EGR temperature sensor and EGR ▪▪ The ECM terminal 29 provides a 5-volt supply to DPS (Delta Position sensor). terminal C of the APP sensor.

46 ISL-G Fuel Systems Inputs

Review Questions Why are there two TPP and APP sensors?

Which is the primary timing reference sensor?

EGR Valve Assembly

The EGR valve position sensors are potentiometers that sense the position of the EGR valve for the ECM. They are 3-wire potentiometers with a 5-volt reference and the motor return for a ground. The Which is the primary engine speed sensor? sensor senses the position of the EGR valve to be in one of three positions and returns this information to the ECM, which keeps fl ow to a maximum of 30% under load. The potentiometers can be tested manually only when the valve is operating. This valve cannot be tested unless the vehicle is under load or in a stall test.

EGR Motor Winding EGR Poppet Valves

ISL-G Fuel Systems 47 Module Two

Activity 1.4: Position Sensors

Cam Speed/Position Sensor

Tools and equipment: 1. Cummins wiring diagram 2. Hand Tool Set 3. DVOM 4. INSITE™

Step 1: Using the repair manual, locate the Cam Speed/Position sensor wiring diagram:

CS/P 5-volt supply Wire terminal ______CS/P Signal Return Wire terminal ______CS/P Sensor Signal Wire terminal ______

Step 2: Do the wire terminals of the wiring diagram and the harness coincide? YES Or NO

Step 3: Back-probe the CS/P and perform the following exercise. With the engine running record the following data. Idle (DVOM/DC voltage and frequency) ______1500 RPM (DVOM/DC voltage and frequency) ______

Step 4: Will the engine run without the CS/P? Yes or No Explain! ______

Step 5: What are the codes associated with the CS/P? ______

If the CS/P was defective, what would the INSITE™ display? ______

48 ISL-G Fuel Systems Inputs

Activity 1.4: Position Sensors

Crank Speed/Position Sensor

Tools and equipment: 1. Cummins wiring diagram 2. Hand Tool Set 3. DVOM 4. INSITE™

Step 1: Using the repair manual, locate the Cam Speed/Position sensor wiring diagram:

CS/P 5-volt supply Wire terminal ______CS/P Signal Return Wire terminal ______CS/P Sensor Signal Wire terminal ______

Step 2: Do the wire terminals of the wiring diagram and the harness coincide? YES Or NO

Step 4: Will the engine run without the CS/P? Yes or No Explain! ______

ISL-G Fuel Systems 49 Module Two

Activity 1.4: Position Sensors

Accelerator Pedal Position Sensors 1 and 2

Tools and equipment: 1. Cummins wiring diagram 2. Hand Tool Set 3. DVOM 4. INSITE™

Step 1: Using the repair manual locate the APPS wiring diagram.

APPS Sensor 1 Return Wire terminal ______APPS Sensor 1 Signal Wire terminal ______APPS Sensor 1 5-volt Reference Wire terminal ______APPS Sensor 2 Return Wire terminal ______APPS Sensor 2 Signal Wire terminal ______APPS Sensor 2 5-volt Reference Wire terminal ______

Does it have an Idle Validation Switch? Yes or No

Step 2: Visually locate APPS sensor and identify the wiring harness. Do the wire terminals of the wiring diagram and harness coincide? Yes or No

Step 3: Using two DVOMs connect the positive lead to APPS Signal wire for sensors 1 and 2, record the following measurements: KEY ON ENGINE OFF (KOEO) Without depressing the accelerator pedal, what is the APPS sensor signal voltage 1______2______Depress the accelerator pedal 50%, what is the APP sensor signal voltage 1______2______Fully depress the accelerator pedal. What is the APP sensor signal voltage 1______2______

Step 4: Using parameter ID from INSITE™ for APPS 1 and 2, record the following measurements: KEY ON ENGINE OFF (KOEO) Without depressing the accelerator pedal, what is the APP sensor signal voltage 1_____ 2______Depress the accelerator pedal 50%, what is the APP sensor signal voltage 1______2______Fully depress the accelerator pedal. What is the APP sensor signal voltage 1______2______

50 ISL-G Fuel Systems Inputs

Activity 1.4: Position Sensors

Accelerator Pedal Position Sensors 1 and 2

Tools and equipment: 1. Cummins wiring diagram 2. Hand Tool Set 3. DVOM 4. INSITE™

Step 1: Using the repair manual locate the TPS wiring diagram.

TPPS1 Sensor Signal Wire terminal ______TPPS2 Sensor Signal Wire terminal ______TPPS 5-volt Reference Wire terminal ______TPPS Sensor Return Wire terminal ______

Step 2: Locate the TPPS sensor and identify the wiring harness. Do the wire terminals of the wiring diagram and harness coincide? Yes or No

Step 3: Using two DVOMs connect the positive lead to APPS Signal wire for sensors 1 and 2, record the following measurements: KEY ON ENGINE OFF (KOEO) Without depressing the throttle pedal, what is the TPPS1 & 2 sensor signal voltage ______Fully depress the throttle pedal. What is the TPPS 1 & 2 sensor signal voltage ______

Step 4: Using INSITE™ observe and record the following readings: KEY ON ENGINE RUNNING (KOER) Without depressing the throttle pedal, what is the parameter ID for TPPS1 and 2 ______Depress the throttle pedal 50%, what is the parameter ID for TPPS1 and 2 ______SNAP the throttle pedal. What is MAX reading observed for TPPS1 and 2 ______

Was there a difference between the readings in step 3 vs 4? If so why?______

ISL-G Fuel Systems 51 Module Two

Signal Producing Sensors conductive. The two platinum electrodes then act as the plates of a battery, with the zirconia acting as the Signal producing sensors create a signal when they electrolyte of the battery. The galvanic reaction cre- operate. This signal may be a voltage, current or fre- ates a voltage output between .1 and .9v. This sensor quency signal, depending upon the type of sensor. can be coated and have false readings when EGR cooler leaks into system. Catalyst Inlet Oxygen Sensor The Catalyst Inlet Oxygen Sensor is mounted in the turbocharger adapter housing, which is the path when the exhaust exits the turbo and goes to the

catalytic converter. The catalyst O2 sensor determines the amount of oxygen in the exhaust gas. The amount of oxygen in the exhaust gas indicates the actual air/fuel ratio information that is used by the ECM to calculate the proper amount of fuel required during closed-loop operation. Catalyst Inlet Oxygen Sensor

The Inlet O2 sensor’s output is used by the ECM to verify that the fuel control valve position and the throttle plate actuator position are providing the desired exhaust gas condition. The ECM can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the ECM to make sure that the engine is run- Outlet Oxygen Sensor Outlet O Connector ning at close to the ideal or stoichiometric point, and 2 also to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to oxidize Catalyst Outlet Oxygen Sensor the unburned hydrocarbons and CO. The Catalytic Outlet Oxygen sensor is mounted at the outlet of the Catalytic converter. It senses the exiting The catalyst inlet O2 sensor consists of two platinum exhaust to confirm proper catalytic converter opera- electrodes separated by a Zirconia (ZrO2) element. tion. It functions in the same manner as the catalyst The outer platinum electrode is exposed to the ex- inlet oxygen sensor, but is used to verify cat opera- haust gas. The inner platinum electrode is vented tion and is not used to determine the proper air/fuel to the atmosphere, in some cases through the lead ratio. wires. When heated to above approximately 700°F (370°C) by the heater element and exhaust tempera-

ture, the zirconia element in the O2 sensor becomes

52 ISL-G Fuel Systems Inputs

The output of this sensor is used by the ECM for ver- You must use a DSO to measure rise time as you ification of proper operation of the three-way catalyst. CANNOT see rise time or measure it accurately with When operating efficiently, the rear portion of the a DVOM. The sensor should drive from lean to rich catalytic converter absorbs oxygen to continue the in under 100 ms when the test is performed or the burning of the HC and CO. The voltage is normally sensor is lazy. flat-lined if the oxygen is being absorbed.

The voltage output of the sensor is tested much the Signal Producing Sensors same as the inlet sensor. Because it is usually flat- Two major knock sensor designs are used today: lined in a rich condition (.7-.9V), it won’t fluctuate broadband single-wire and flat response two-wire except during warmup. It can be forced rich and lean knock sensors. Both types are piezoelectric crys- similar to the inlet sensor. tals like the old crystal earphones and microphones that send voltage and frequency signals to the ECM CAUTION: Forcing the system rich can cause that detects engine noise caused by detonation. This damage to the catalyst if done excessively. engine has two knock sensors - each sensor monitors three cylinders. The location of the knock sensors is Testing Heated Oxygen Sensors specific and the knock detection is calibrated for this position. Therefore, knock sensors must not be reposi- The voltage output of the sensor is read using an tioned from the original location. electronic service tool such as INSITE™ or manually tested using a voltmeter or digital storage oscilloscope. Combustion Knock Sensors The sensor should be capable of reaching both .1 and 1 and 2 .9V thresholds when driven lean and rich. Propane The ECM has three thresholds programmed into it for enrichment is used to drive the system lean. The time knock detection and prevention. it takes to return to a rich condition is called the Rise Time of the sensor. When detonation is sensed, the ECM retards engine timing until detonation is diminished. Over time, the ECM will attempt to restore normal timing if detonation diminishes.

Light Knock: Lowest of the three thresholds, is designed to guard against damage from light to mild knock. The ECM will retard ignition timing and slightly de-rate the throttle. A yellow lamp will illuminate to warn the operator that light knock has been detected.

Testing O2 Sensor Manually

ISL-G Fuel Systems 53 Module Two

Heavy Knock: This warning will be activated if the Both sensors work the same and are tested the same. light knock protection fails to eliminate the problem Care must be taken to eliminate other sources of or a knock is detected that crosses the heavy knock knock, such as noise caused by improper timing of threshold. The ECM will trigger a severe throttle de- the compressor. rate and illuminate the red warning lamp.

Cold Knock Threshold: This provides severe pro- Combustion Knock Control tection while the engine is reaching a stable operat- Systems ing temperature. Time at this threshold is a function A knock sensor’s a common pattern is an alternat- of coolant temperature at startup. The cold knock ing signal (AC) with the frequency changing to threshold is disabled when the engine temperature match the noise of the knock. It is sometimes very reaches 160 °F (71 °C). weak and often difficult to monitor on a conventional lab scope. PICO scopes are more effective to ▪▪ The knock sensors are located near the front and see weak signals as they can amplify the trace. A rear of the engine. DVOM must have the proper frequency range to pick up the signal. ▪▪ The front knock sensor listens to cylinders 1,2,3 for detonation.

▪▪ The rear knock sensor listen to cylinders 4,5,6 for detonation.

An ohmmeter can be used to check continuity. Deto- nation can be monitored with INSITE™ or you can create a simulated knock and monitor with an oscilloscope or DVOM with a frequency function.

Knock Sensor Connector

Rear Knock Sensor

54 ISL-G Fuel Systems Inputs

Review Questions

What is the voltage range of a normal O2 sensor?

What is wrong if it stays above .45V?

Why are there two knock sensors?

ISL-G Fuel Systems 55 Module Two

Activity 1.5: Signal Producing Sensors

Catalyst Inlet and Outlet Oxygen Sensors

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. DVOM 3. INSITE™ 4. Propane Enrichment Tool

Step 1 Using the classroom manual, locate the Catalyst Inlet and Outlet Oxygen Sensor wiring diagram:

Inlet Outlet HOS signal Wire terminal ______HOS signal return Wire terminal ______12v heater supply Wire terminal ______12v heater return Wire terminal ______

Step 2: Do the wire terminals of the wiring diagram and the harness coincide? YES Or NO

Step 3: Connect to the DVOM. Connect Insite and view the HO2S PID. Key On Engine Running (KOER).

Step 4: Insert a propane enrichment tool into the intake system. Open the propane valve to create a rich mixture over 800mv. Close the valve and create a lean mixture under 75mV. Snap the throttle and measure the rise time under 100ms.

Observations: ______

Step 5: Repeat step 1-4 with the Catalyst Outlet Oxygen Sensor.

56 ISL-G Fuel Systems Inputs

Step 6: (Optional pending INSITE™ availability) Note the readings of the FUEL CONTROL VALVE while performing the propane enrichment exercise and write the value in the space provided. ______

Note the readings of the FUEL CONTROL VALVE while performing the FULL STALL TEST without propane enrichment and write the value in the space provided. ______

Note the readings of the FUEL CONTROL VALVE @ idle and write the value in the space provided. ______

ISL-G Fuel Systems 57 Module Two

Mass Sensing The signal from the Mass Gas Sensor represents low voltage = low flow and high voltage = high flow, as Mass sensors measure the volume of material that is these values are monitored in INSITE™. A major going past it. This is used to determine flow of air or concern with this sensor is that oil contamination that gas into the engine. can come in with the fuel can coat this sensor and give false readings. This would result in poor perfor- mance and efficiency. Mass Gas Sensor This sensor, mounted in the fuel housing, operates the A DVOM can be used to monitor the voltage change same as all hot-wire type flow sensors. It is used to at the signal wire and return. INSITE™ can also be sense the flow of gas into the control valve. used to monitor the sensor activity.

A heated element is cooled by the flow of the gas NOTE: This sensor requires a 15-volt supply and the ECM ramps up current to maintain a prede- to operate properly. There is a voltage am- termined temperature of the sensing wire. A NTC plifier circuit in the ECM that steps up the (Negative Temperature Coefficient) thermistor mea- voltage to this sensor. This is the only sensor sures the temperature of the sensing wire and signals requiring 15 volts. the ECM of measured temperature. The amount of current (displayed in voltage) determines the volume Mass Air Flow Sensor or mass of fuel that is flowing and becomes part of The Mass Airflow (MAF) sensor, mounted on the the fuel trim formula. inlet of the mixer housing, is a hot-wire type flow sensor with an air temperature sensor included. It functions to determine the amount of airflow entering the engine to calculate the base fuel delivery for the current engine operating condition. The sensors are calibrated for the engine size and flow.

This sensor uses a hot-wire type sensor that heats up Mass Gas Sensor Sensor Element with Connector Thermistor and is cooled by the incoming air, with the resulting wind chill factor determining the volume. The sensor has a bypass circuit that gathers approximately 10% of the flow and directs it past the hot-wire element. The sensor is heated to a specified temperature and the current increase required to maintain that temperature is used to calculate airflow into the engine. The temperature of the incoming air is critical to this calculation so it includes a thermistor in the circuit. In open-loop, this predicted airflow information

Mass Gas Sensor

58 ISL-G Fuel Systems Inputs

becomes the base fuel trim while in closed loop, the O2 sensors make minor adjustments to this base calculation.

Sensor on Throttle Connector

MAF Sensor and MAF Thermister

Mass Airﬂ ow (MAF) Sensor

The sensor is a separate computer circuit that changes voltage input to the ECM as the current changes due to the wind chill effect on the hot -sensor. The cur- Review Questions rent needed to overcome the voltage drop across the wire is proportional to the mass of airfl owing past the What type of sensors are the Mass Gas and Mass wire. The ECM uses this information to calculate the Airfl ow? fuel trim. Testing of the sensor can be done by mon- itoring a voltmeter on the signal wire or INSITE™ while changing intake volume. The air temperature sensor can also be manually tested with a voltmeter and an infrared temperature probe.

Why is there an air temperature sensor in the Mass Airfl ow Sensor?

ISL-G Fuel Systems 59 Module Two

Activity 1.6: Cummins Mass Sensing

Mass Gas Sensor

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. DVOM 3. INSITE™ (optional)

Step 1: Using the repair manual locate the Mass Gas Sensor wiring diagram.

Mass 15-volt Supply Wire terminal ______Mass Sensor Return Wire terminal ______Mass Signal Return Wire terminal ______Mass Sensor Signal Wire terminal ______

Step 2: Locate the Mass Gas sensor and identify the wiring harness. Connect DVOM to Mass Sensor Signal and Signal Return. Connect INSITE™ (optional) and view the Mass Ssensor parameters.

Step 3: Record the following measurements at some of the specified RPM readings below to create a graph.

6.0V 5.5V 5.0V 4.5V 4.0V 3.5V 3.0V 2.5V 2.0V 1.5V 1.0V 0.5V RPM 800 950 1100 1250 1400 1550

60 ISL-G Fuel Systems Inputs

Activity 1.6: Cummins Mass Sensing

Mass Air Flow Sensor

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. DVOM 3. INSITE™ (optional)

Step 1: Using the repair manual locate the Mass Gas Sensor wiring diagram

Mass 12-volt Supply Wire terminal ______Mass Sensor Return Wire terminal ______Mass Air Flow Signal Wire terminal ______Mass Signal Return Wire terminal ______Air Temperature Signal Wire terminal ______

Step 2: Locate the Mass Air sensor and identify the wiring harness. Connect DVOM to Mass Sensor Signal and Signal Return and set to measure frequency. Connect INSITE™ (optional) and view the Mass sensor parameters

Step 3: Note: If using the DVOM to measure frequency, the units of measure will be (KHz). If using INSITE™, your units of measure will be lbs/hr.

Record the following measurements at the specified RPM readings to create a graph.

ISL-G Fuel Systems 61 Module Two

5 KHz 4.75 KHz 4.5 KHz 4.25 KHz 4.0 KHz 3.75 KHz 3.5 KHz 3.0 KHz 2.75 KHz 2.5 KHz 2.25 KHz 2.0 KHz 1.75 KHz 1.5 KHz 1.0 KHz .75 KHz .5 KHz .250 KHz RPM 800 950 1100 1250 1400 1550

62 ISL-G Fuel Systems Inputs

Turbocharger Compressor Inlet that is immersed in the fluid. It must be mounted Humidity Temperature Sensor vertically when replaced and has a different testing procedure than switches or resistance sensors. The The compressor inlet temperature and humidity sensor can leak internally, shorting the connector sensor measures the temperature and water content of pins, causing stalls, de-rated power, etc. the incoming air. The incoming air will have varying amounts of oxygen based upon its density and water content that will have an effect on stoichiometry ICM Spark Voltage and Misfire calculations. Cold air will have more oxygen, as will Signals damp air so the ECM adjusts its fuel delivery and timing to accommodate these changes. The ICM has a built-in engine ignition diagnostic capability. The ICM monitors individual spark Testing the humidity part of the sensor is difficult as plug voltage and misfires and reports it to the ECM this is a “smart sensor”. This means that it contains a as an input for diagnostic purposes only. Ignition microprocessor that generates a Controller Area Net- timing and air/fuel mixture values are not affected work (CAN) signal that is broadcast on the CAN bus by these signals. and interpreted by the ECM. The ICM provides kV and misfire detection as an input to the ECM for diagnostic fault code capability. Coolant Level Sensor This engine incorporates multiple spark discharge technology that uses solid state devices to trigger the The coolant level sensor is mounted in the reservoir to capacitor charge/discharge cycle very rapidly when monitor coolant level. It is a capacitance-type sensor. the engine has low intake manifold pressure. During this condition, there is a relatively small amount of When the coolant level drops below a certain level, the air/fuel mixture in the cylinder, and the cylinder is ECM will de-rate the engine. The level of de-rate be- relatively cool. It is possible for the flame created by comes greater with time if the problem is not corrected. the spark to ‘quench’, that is extinguish, due to the The ECM will use this input to de-rate or shut down low heat and sparse air/fuel mixture in the cylinder. the engine, depending on customer parameters. Misfires can send unburned fuel and oxygen to the catalytic converter, overheating it and damaging the The engine coolant level sensor is a capacitance-type substrate. Any misfires should be addressed to pre- sensor that works by changing capacitance on a wire vent this damage from occurring.

Testing can only be done on the primary side or with INSITE™. Primary resistance can be tested as well as the secondary windings for shorts to ground with an ohmmeter.

Coolant Level Sensor Connector

ISL-G Fuel Systems 63 Module Two

CAUTION: Misfires can damage the catalyst, The Can Networks communications system can have which can be very expensive. Cylinder bal- several protocols. Testing the system involves check- ance tests have been eliminated from IN- ing the wiring for continuity and using INSITE™ to SITE™ to prevent this. check the communications.

CAN, J1939 and J1587 Data Bus Switched ECM Inputs The CAN data bus parameters are available for net- There are various switched inputs to the vehicle ECM work communications. They are broadcasted by the to provide operator requested commands. These ECM and are internal to the engine body and wiring include PTO parameters and feature adjustment con- harness. trol. Many of these items are accessories or special features that may not be present on the vehicle. ▪▪ The J1939 data-link with the INSITE™ diagnostic tool can be connected to this data-link to The switched inputs include several on/off switches like: communicate with the ECM. ▪▪ J1587 communications for OEM systems includ- ▪▪ Override normal throttle operations ing engine. This line is slower than the 1939. ▪▪ Operate requested accessories ▪▪ Prevent starter motor operation without clutch ▪▪ Diagnostic tool interface provided at engine and depress other location based on OEM application. ▪▪ Override cooling fan automatic operation ▪▪ Twisted-pairs of wires to reduce Electromagnetic ▪▪ Enter diagnostic functions Interference and Radio Frequency Interference (EMI and RFI). Switched inputs are pulled low to engage so the ECM ▪▪ 120 Ω terminating resistors to provide proper sees the voltage change on the line from high to low. electrical load to circuit and to determine the start and end of the network connections.

The network protocol is used to communicate with other networked controllers. Several different protocols are utilized depending upon the speed of transmission needed for the component being monitored. Some components use the lower priority protocols as the reduced baud rate is not important. Other items require higher speeds to operate properly.

You should only use J1939 Protocol on the engine for fastest updating with the INSITE™ service tool.

64 ISL-G Fuel Systems Inputs

ISL-G Fuel Systems 65 Module Three 3

66 ISL-G Fuel Systems Outputs

Outputs, Actuators, Solenoids, than 10% change, and check for sticking.The digital and Signals lab scope is the preferred method to view the pulse- width signal aside as INSITE™ will only provide the The outputs of the ECM are controlled by drivers duty-cycle as a parameter. that operate the work producing components. The ECM will actuate these components when conditions require them. Most of these components are electro-magnets of some type that the computer grounds to turn on. It is easier for the ECM to control the ground on so these are referred to as “ground side switched” components. Lamps and communication signals, such as ignition and parameter display connections, are also outputs of the ECM.

Control Valve Fuel Control Valve The Fuel Control valve is the solenoid operated injector that delivers the fuel to the engine. It is mounted in the fuel housing and is pulse width modulated to determine its on-time.

This is a two wire (n/c) normally closed valve. This is like one large injector that delivers fuel to the mixer instead of one for each cylinder. This valve is known to stick, or the coil can open. Remember that the ECM commands this valve and does not confirm Control Valve Connector that the valve is functioning properly other than by getting feedback through the Mass Gas Sensor.

The Fuel Control valve is a normally closed valve, similar to other engine models, with inlet and outlet ports calibrated for the engine flow rate. They are different sizes with double O-ring seals to prevent fuel leakage. This valve is pulse-width modulated solenoid as are conventional injectors.

INSITE™ provides a duty-cycle parameter for this solenoid. When checking this valve, check for resistance (3-5 ohms) both hot and cold with no more

ISL-G Fuel Systems 67 Module Three

Wastegate Control Valve This valve is what we call “high-side” controlled as The wastegate is a port on the turbocharger that the ECM powers up the valve to actuate it instead of dumps the exhaust pressure away from the turbo- grounding it. This is done for a safety factor to pre- charger to control its output pressure. The control vent accidental grounding of the solenoid valve and valve, located in the inlet of the mixer housing, unwanted actuation. provides pressure to the wastegate, which opens and diverts the exhaust stream away from the blades of To test this valve, use an ohmmeter to test the sole- the turbo. noid coil. In addition, the signal to this valve is PWM so the duty can be tested for this valve. Higher-duty The default closed position of the waste control valve cycle will equal more boost. allows full boost pressure to act on the wastegate in the event there is a malfunction of the valve or of the various sensors that monitor boost pressure. In normal operation, the valve bleeds off pressure applied to the wastegate to allow for increases in turbo boost pressure as load or power requirements dictate.

This valve is a 2-wire solenoid and will limit boost to 5 psi if the valve malfunctions. Checks for continuity and valve movement can be accomplished. This valve Wastegate Control Valve can only be operationally tested while under load.

The control valve is a normally closed valve that is opened by a signal from the ECM, based upon mixer inlet pressure. The ECM pulses the solenoid on and off rapidly to achieve the desired boost pressure using Pulse Width Modulation (PWM). The on-time of the sensor is measured in milliseconds (ms) with a longer pulse width resulting in more fuel being delivered.

Connector

Wastegate Control Valve

68 ISL-G Fuel Systems Outputs

Activity 1.7: Cummins Control Valves

Fuel Control Valve

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. INSITE™ 3. Hand Tool Set 4. DVOM

Step 1: Locate the Fuel Control Valve and identify the power and ground wires:

#1 ground Wire terminal ______#1 power Wire terminal ______

Step 2: Using a propane enrichment tool, inject fuel into the intake manifold and proceed to step 3.

Step 3: Using the DVOM and INSITE™(optional), record the following readings in the space provided.

What is the FCV reading @ KOEO? DVOM ______INSITE™ ______

What is the FCV reading @ idle (no propane)? DVOM ______INSITE™ ______

What is the FCV reading @ full stall? DVOM ______INSITE™ ______

What is the FCV reading @ idle (with propane)? DVOM ______INSITE™ ______

Step 4: What is the Mass Gas Flow Compensation according to INSITE™ prior to propane enrichment? ______%

Step 5: What is the Mass Gas Flow Compensation according to INSITE™ while performing the propane enrichment. ______%

ISL-G Fuel Systems 69 Module Three

Throttle Actuator Fuel Shut-Off Valve The throttle actuator is located on the front side of the The fuel shut-off valve is located in the fuel housing intake manifold/mixer housing. It is used to control under the secondary regulator. It is used to allow the engine speed through “Drive by Wire” throttle. The natural gas to enter the system. It is a normally closed ECM controls the throttle plate opening based upon 12V valve operated by the ECM. demand from the driver and need.

The ECM sends a pulse width modulated (PWM) signal to the throttle plate actuator motor. The throttle plate actuator opens or closes the throttle plate in response to the PWM signal. This actuator also has position sensors that report the throttle position information back to the ECM.

Fuel Shut-Off Valve

As dictated by California law (CHP title 13), all combustible-fueled engines must have a means to stop fuel flow to the engine in the event the engine dies or the fuel lines become damaged. NG engines use two shutoff valves to automatically close in the event the engine RPM signal is lost or the ignition switch is turned Throttle Actuator Assembly off. This is controlled by the ECM, which shuts off the valve if engine RPM is not present or < 100 RPM. This signal is based upon demand for load by APP1 and APP2, the two Accelerator Pedal Position Sensor This valve is in the low-pressure stream that opens signals that are sent to the ECM based upon driver’s when energized to allow fuel flow. input (pedal position). To test the valve, back-probe the connector at pin The throttle actuator 6-wire plug has the 5-volt refer- C while cranking and you should see 12 volts. The ence with a common return. The voltage is pulsed to resistance with the connector disconnected should be ATA- and ATA + as a command to open and close 3 to 5 ohms. Resistance should be checked when the the throttle. PP1 and TPP2 are sensor signals to the valve is both hot and cold and should not vary more ECM that identify the position of the throttle plate. than 10%.

70 ISL-G Fuel Systems Outputs

Activity 1.8: Cummins Control Valves

Fuel Shut-off Valve

Tools and equipment: 1. Cummins Troubleshooting and Repair Manual 2. Hand Tool Set 3. DVOM 4. INSITE™ (Optional)

Step 1: Visually locate the Fuel Shut-off Valve and identify the power and ground wires:

#1 ground Wire terminal ______#1 power Wire terminal ______

Step 2:

Using a DVOM, record the following readings in the space provided.

Connect INSITE™ and view the Fuel Shut-Off Valve parameters(Optional)

What is the FSV reading @ KOEO? DVOM ______INSITE™ ______

What is the FSV reading as engine starts to crank? DVOM ______INSITE™ ______

What is the FSV reading while engine cranks? DVOM ______INSITE™ ______

What engine activity turns on the FSV? DVOM ______INSITE™ ______

What is the FSV reading @ KOER? DVOM ______INSITE™ ______

Turn off the engine.

What is the FSV reading @KOEO? DVOM ______INSITE™ ______

ISL-G Fuel Systems 71 Module Three

Electronic EGR Valve When the engine first starts and until it warms up, the ECM prevents the EGR valve from operating. The EGR Valve is controlled by the ECM and regu- When the engine is at operating temperature, the lates the amount of re-circulated exhaust gases that EGR valve flow is influenced by the position of the enter the intake manifold. The EGR valve lets some throttle under load. This is generally at light throttle exhaust gases pass into the intake system. During openings, when a lean mixture could cause increased combustion, these gases displace volume in the com- oxides of nitrogen.It does not operate at idle, or at bustion chamber with inert gases that will not burn. wide-open throttle. Exhaust gases have very little oxygen and will not combust. This lowers peak combustion temperatures, Oxides of nitrogen can also be reduced by retarding and reduces formation of oxides of nitrogen, because ignition timing. This lowers the maximum tempera- nitrogen and oxygen bond under high heat (over ture reached during combustion. The maximum 2500 °F) and the formation of NOx is reduced. ignition-advance setting is then said to be “emis- sion-limited”. However, it also lowers engine output, and increases fuel consumption.

This is a three-position valve and the ECM manages this valve by keeping EGR flow from the exhaust into the mixer at a maximum of 30%. EGR flow only takes place when the engine is under load and never at idle. Because of this, the EGR Valve can only be tested under load or in a stall.

A stuck-open EGR valve can result in rough idle or EGR Valve stalling. A stuck-closed EGR valve may produce high NOx and knocking.

ECM controls the EGR valve with a PWM (pulse width modulated) signal.

This command is based upon the EGR differential pressure between the exhaust manifold and the mixer and the temperature.

With a PWM command signal, the EGR motor pushes a rod down against the poppet valve, which is spring loaded on the bottom, and the three sensors mounted 3 Position Valve in different locations verify location of rod with inputs

72 ISL-G Fuel Systems Outputs

from the EGR PDS and the EGR temperature sensor it Control and Data Signals able make constant adjustments to EGR Flow. There are many outputs from the ECM that are used The EGR valve has three EGR control motors and to control engine functions. These include: 3 potentiometers as EGR position sensors. They all share a 5 volt power supply and the motor return for ▪▪ CAN Data communications a ground. The ECM controls the motors and receives ▪▪ Starter lockout signal input from the position sensors. ▪▪ Fan Control signal

Ignition Control Module The ignition control module is a slave of the ECM. It has the firing order in memory and, with a timing and TDC reference signal from the ECM, operates the coils in the firing order of the engine.

Electronic EGR

Warning and Indicator Lamps This engine has three lamps to alert/notify the driver of problems.

▪▪ Yellow Lamp – Warning lamp illuminates with

some fault codes and pending items ECM/ICM ▪▪ Red – Stop Lamp warns of pending shutdown and serious faults needing attention.

▪▪ Blue – Maintenance required Lamp

ISL-G Fuel Systems 73 Module Three

Coil Over Plug Ignition shaft Speed Position Sensor becomes the primary input for ignition timing. The ECM also uses input from This engine uses a coil-on-plug type of ignition coil. the Intake Manifold Pressure Temperature Sensor to This coil mounts directly to the spark plug. The adjust how far to advance the timing of the spark. high-voltage pulse from the secondary windings of the coil are delivered directly to the spark plug. This To determine if an ignition coil is operational and pro- system eliminates traditional spark plug wires, result- ducing the high voltage required to create a spark at ing in less maintenance and a more efficient transfer the plug, an approved ignition coil spark tester is rec- of electrical energy from the coil to the plug. ommended. For the ISX12G engine, the COP must be kept nearly vertical during operation due to oil filled cooling of the coil. The test kit adapter must be used to properly position the COP during spark testing on this engine. When using this tester, no attempt should be made to adjust the tester. The ignition coil tester is preset and is not adjustable. Attempts to adjust the tester will damage the tool. The secondary winding measurement for the COP resistance is taken between the spark plug connection and either pins B or C of the 4-pin connector for the CM2180A ECM.

The Engine Camshaft Speed/Position Sensor provides Coil Over Plug Ignition engine speed and cylinder #1 compression stroke information to the ECM. This sensor generates a signal from the passing of seven cast protrusions located on the rear of the camshaft gear. An engine Crankshaft Position Sensor mounted at the rear of the block is used to signal piston position during the stroke. Both of the ISX12G position sensors are Hall-Effect type and provide a DC high-low (5 to 0V) signal to the ECM. The engine Crankshaft Speed/Position Sensor is located on top of the flywheel housing. The information from this sensor is used by the ECM to determine crankshaft rotational speed and each cylinder’s CPS Crank Position Sensor piston position as it relates to degrees of crankshaft rotation. The ECM requires an initial input from the Camshaft Speed Position Sensor in order for the engine to start. These are what’s called “piezo electric” devices. Once the ECM gets synchronization from this sensor When the gallium crystal vibrates at a specific fre- and the Crankshaft Speed Position Sensor, the Crank- quency that is associated with engine detonation

74 ISL-G Fuel Systems Outputs noise, it resonates and produces a small amount of AC Review Questions current. This is a very weak signal and only high-end oscilloscopes may be able to display it. INSITE™ What is the voltage supplied from the ICM to the parameter display is probably the best way to see if it coil? is working.

The ISL-G uses a special plug design with 3 electrodes for effi ciency and dependability. The replacement kit includes the plug and a pre-greased replacement boot. Where is this voltage stored?

Never use a socket with a rubber retainer insert. The rubber insert can leave a residue on the plug porce- lain and lead to carbon tracking. Use a magnetic plug socket such as the Snap-On #S9706KMAG. Plugs should never be re-gapped as the coating on the elec- What is the installation procedure for spark plugs? trodes will be damaged. Clean plugs and sockets with denatured alcohol and torque to (28 ft. lbs.). This is critical for proper plug life.

Spark plugs work very hard to do their job and are under appreciated. At 2000 RPM one plug is fi ring Why are these steps so important? over 16 times per SECOND regardless of the load on the engine. The plugs do wear out and will misfi re under a load as well. This puts a lot of stress on a plug over its intended life so maintenance intervals are approximate only. The use of proper plugs torqued to the proper specifi cations will help this interval.

A general rule for plugs is: when in doubt, change them out.

3-Electrode Plug

ISL-G Fuel Systems 75 Test

Post Test ISL-G Fuel Systems

1. What sensor is used to monitor the Air/Fuel Ratio? a. Engine Coolant Temperature Sensor Pressure Sensor

b. O 2 Sensor c. Engine Manifold Pressure Sensor d. Engine Manifold Temperature Sensor

2. What is closed-loop? a. ECM gets the air fuel mixture data from the Exhaust Temperature Sensor b. ECM gets the air fuel mixture data from the Engine Coolant Sensor c. ECM gets the air fuel mixture data from the Engine Manifold Pressure Sensor

d. ECM gets the air fuel mixture requirements from the O2 Sensor 3. Can a malfunctioning ECT cause a no-start/hard start condition? a. True b. False

4. What is the function of temperature sensors? a. Equates a resistance to a temperature b. Equates a temperature to a resistance c. Equates a current to a resistance d. Equates a voltage to a temperature

5. What sensor acts as a choke for fuel enrichment? a. Turbine Temperature Sensor b. Intake Manifold Pressure Sensor c. Engine Coolant Temperature Sensor d. EGR Temperature Sensor

7. TWC means ______and ______has to happen for it to work correctly? a. Two-way Catalyst, Lean-Burn b. Three-way Catalyst, Stoichiometry c. Three-way Catalyst, Lean-Burn d. Ten-way Catalyst, Stoichiometry

8. What is the threshold voltage for the O2 Sensor to go between lean and rich? a. .60V b. .25V c. .45V d. .75V

76 ISL-G Fuel Systems ISL-G Fuel Systems 77 Natural Gas Safety Considerations

TOXICITY: Nontoxic it is not a poison like carbon COLLISION: Cylinders must have a Detailed monoxide but it does displace oxygen. Visual Inspection and hardware should be carefully inspected for damage. Cylinders should be closed and ¼ turn valve closed if vehicle is involved in an FLAMMABILITY: Flammability range is narrow accident 5-15% -- below 5 is too lean to burn above 15 too rich. Edges of a cloud could be right mixture. Heaters and other spark producing items must be STORAGE: LNG vehicles should be stored outside relocated. due to venting of tank. CNG system are sealed and will not leak to atmosphere

VENTILATION: Must be trapped vertically to be dangerous - look up for traps at ceiling/false ceilings SHOP SAFETY/EQUIPMENT: Methane detectors etc. Lighter than air so most shops are equipped and ceiling ventilation should be reviewed by with auto vents on the methane detection circuit. engineering. Special tools kit being provided to perform defueling etc.

LEAK DETECTION: Mercaptin NOT present in LNG unless infused so it will have no odor. Methane detectors and hand held combustible gas detectors available along with commercial bubble style leak detectors. CG detectors will go off on many substances such as glycol, silicone, diesel, hyd. fluid so it is just a gross indicator.

78 ISL-G Fuel Systems ISL-G Fuel Systems 79 References

Sources: Publications:

Compressed Gas Association CGA C-6.4, “Methods for External Visual 1725 Jefferson Davis Highway, Inspection of Natural Gas Vehicle Fuel #1004 Arlington, VA 22202-4102 Containers and Their Installations,” 1st Telephone: 703-412-0900 Edition (1997)

Gas Research Institute NFPA 52, “Standards for Compressed 8600 W. Bryn Mawr Avenue Natural Gas Vehicular Fuel Systems” Chicago, IL 60631-3652 National Fire Protection Association, Telephone: 773-399-8352 1 Batterymarch Park, Box 9101, Quincy, MA 02269-9101 American National Standards Institute 11 W. 42nd Street ANSI/AGA-NGV2, “ Basic Requirements for New York, NY 10036 Compressed Natural Gas Vehicle Fuel Telephone: 212-642-4900 Containers,” American Gas Association Laboratories, 8501 East Pleasant Valley National Fire Protection Association Road, Cleveland, OH 44131 11 Tracy Drive Avon, MA 02322 FMVSS304, “Compressed Natural Gas Fuel Telephone: 800-593-6372 Container Integrity,” Federal Motor Vehicle Safety Standards, US DOT, NHTSA Natural Gas Vehicle Coalition 1515 Wilson Blvd. Suite 1030 Gas Research Institute, “ Natural Gas Arlington, VA 22209 Vehicle Cylinder Care and Maintenance Telephone: 703-527-3022 Handbook” (1997)

Department of Transportation CHP Title 13 400 Seventh Street, SW Washington, DC 20590 Telephone: 202-366-4000

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