TJ IGNITION CONTROL 8I - 1 IGNITION CONTROL TABLE OF CONTENTS page page IGNITION CONTROL OPERATION - 4.0L .......................8 DESCRIPTION ..........................1 REMOVAL - 4.0L .........................8 OPERATION ............................1 INSTALLATION - 4.0L ....................10 SPECIFICATIONS COIL RAIL - 4.0L SPECIFICATIONS - IGNITION TIMING .......2 DESCRIPTION - 4.0L ....................10 ENGINE FIRING ORDER - 2.4L 4-CYLINDER . 2 OPERATION - 4.0L ......................11 ENGINE FIRING ORDER - 4.0L 6-CYLINDER REMOVAL - 4.0L ........................11 ENGINE ..............................2 INSTALLATION - 4.0L ....................12 IGNITION COIL RESISTANCE - 2.4L ........2 IGNITION COIL - 2.4L IGNITION COIL RESISTANCE - 4.0L ENGINE . 3 DESCRIPTION - 2.4L ....................13 SPARK PLUGS ........................3 OPERATION - 2.4L ......................13 SPECIFICATIONS - SPARK PLUG CABLE REMOVAL - 2.4L ........................13 RESISTANCE .........................3 INSTALLATION - 2.4L ....................13 SPECIFICATIONS - TORQUE - IGNITION SPARK PLUG SYSTEM .............................3 DESCRIPTION .........................13 AUTO SHUT DOWN RELAY OPERATION ...........................13 DESCRIPTION - PCM OUTPUT .............4 DIAGNOSIS AND TESTING - SPARK PLUG OPERATION CONDITIONS .........................14 OPERATION - ASD SENSE - PCM INPUT ....4 REMOVAL .............................16 OPERATION - PCM OUTPUT .............4 CLEANING DIAGNOSIS AND TESTING - ASD AND FUEL CLEANING SPARK PLUGS ..............16 PUMP RELAYS ........................4 INSTALLATION .........................17 REMOVAL .............................5 SPARK PLUG CABLE INSTALLATION ..........................5 DESCRIPTION .........................17 CAMSHAFT POSITION SENSOR - 2.4L OPERATION ...........................17 DESCRIPTION - 2.4L .....................5 DIAGNOSIS AND TESTING ................17 OPERATION - 2.4L .......................5 REMOVAL - 2.4L ........................18 REMOVAL - 2.4L .........................6 INSTALLATION .........................18 INSTALLATION - 2.4L .....................6 CAMSHAFT POSITION SENSOR - 4.0L DESCRIPTION - 4.0L .....................7 IGNITION CONTROL OPERATION DESCRIPTION 2.4L The ignition systems used on both the 2.4L 4–cyl- A common ignition coil divided into 2 halves is inder and 4.0L 6–cylinder engines are a distributor- used. Secondary, high-tension spark plug cables are less type. also used. One half of the coil fires two spark plugs The ignition system consists of: simultaneously (one plug is the cylinder under com- ² Spark Plugs pression, and the other plug is the cylinder on the ² Spark Plug Cables (secondary wires) exhaust stroke). Coil half number one fires cylinders ² Ignition Coil(s) 1 and 4. Coil half number two fires cylinders 2 and 3. ² Powertrain Control Module (PCM) The PCM determines which of the coils to charge and ² Crankshaft Position Sensor fire at the correct time. ² Camshaft Position Sensor The Auto Shutdown (ASD) relay provides battery ² The MAP, TPS, IAC and ECT also have an effect voltage to the ignition coil. The PCM provides a on the control of the ignition system. ground contact (circuit) for energizing the coil. When the PCM breaks the contact, the energy in the coil 8I - 2 IGNITION CONTROL TJ IGNITION CONTROL (Continued) primary transfers to the secondary causing a spark. ENGINE FIRING ORDER - 4.0L 6-CYLINDER The PCM will de-energize the ASD relay if it does ENGINE not receive inputs from either the crankshaft or cam- shaft position sensors. A distributor is not used with the 2.4L engine. 4.0L The 4.0L 6-cylinder engine uses a one-piece coil rail containing three independent coils. Although cyl- inder firing order is the same as 4.0L engines of pre- vious years, spark plug firing is not. The 3 coils dual- fire the spark plugs on cylinders 1-6, 2-5 and/or 3-4. When one cylinder is being fired (on compression stroke), the spark to the opposite cylinder is being wasted (on exhaust stroke). The one-piece coil bolts directly to the cylinder head. Rubber boots seal the secondary terminal ends of the coils to the top of all 6 spark plugs. One electrical connector (located at the rear end of the coil rail) is used for all three coils. Because of coil design, spark plug cables (second- ary cables) are not used. A distributor is not used with the 4.0L engine. The ignition system is controlled by the Powertrain Control Module (PCM). FIRING ORDER - 4.0L SPECIFICATIONS SPECIFICATIONS - IGNITION TIMING Ignition timing is not adjustable on any engine. ENGINE FIRING ORDER - 2.4L 4-CYLINDER 1 - 3-4-2 IGNITION COIL RESISTANCE - 2.4L Primary Resistance at Secondary Resistance at Engine Coil Manufacture 21°C-27°C (70°F-80°F) 21°C-27°C (70°F-80°F) 2.4L Toyodenso or Diamond 0.51 to 0.61 Ohms 11,500 to 13,500 Ohms TJ IGNITION CONTROL 8I - 3 IGNITION CONTROL (Continued) IGNITION COIL RESISTANCE - 4.0L ENGINE PRIMARY RESISTANCE 21-27°C (70-80°F) 0.71 - 0.88 Ohms IGNITION COIL - 2.4L SPARK PLUGS ENGINE PLUG TYPE ELECTRODE GAP 2.4L 4-Cylinder RE14MCC5 (Champion #) 1.24 to 1.37 mm (0.048 to 0.053 in.) 4.0L 6-Cylinder ZFR5N (NGK #) 1.00 mm (0.040 in.) SPECIFICATIONS - SPARK PLUG CABLE RESISTANCE MINIMUM MAXIMUM 250 Ohms Per Inch 1000 Ohms Per Inch 3000 Ohms Per Foot 12,000 Ohms Per Foot SPECIFICATIONS - TORQUE - IGNITION SYSTEM DESCRIPTION N·m Ft. Lbs. In. Lbs. Camshaft Position Sensor Mounting Bolts – 4.0L 2 - 15 Camshaft Position Sensor – 2.4L 12 - 106 Ignition Coil Rail Mounting Bolts – 4.0L 29 - 250 Ignition Coil Mounting Bolts – 2.4L 11 - 105 Oil Pump Drive Hold-down Bolt – 4.0L 23 17 - ** Spark Plugs - 2.4L 4-Cylinder 15 11 - Spark Plugs - 4.0L 6-cylinder 30 22 - ** Torque critical tapered design. Do not exceed 15 ft. lbs. torque. 8I - 4 IGNITION CONTROL TJ AUTO SHUT DOWN RELAY DESCRIPTION - PCM OUTPUT The 5–pin, 12–volt, Automatic Shutdown (ASD) relay is located in the Power Distribution Center (PDC). Refer to label on PDC cover for relay location. OPERATION OPERATION - ASD SENSE - PCM INPUT A 12 volt signal at this input indicates to the PCM that the ASD has been activated. The relay is used to connect the oxygen sensor heater element, ignition Fig. 1 ASD and Fuel Pump Relay Terminals—Type 1 coil and fuel injectors to 12 volt + power supply. This input is used only to sense that the ASD relay is energized. If the Powertrain Control Module (PCM) does not see 12 volts at this input when the ASD should be activated, it will set a Diagnostic Trouble Code (DTC). OPERATION - PCM OUTPUT The ASD relay supplies battery voltage (12+ volts) to the fuel injectors and ignition coil(s). With certain emissions packages it also supplies 12–volts to the oxygen sensor heating elements. The ground circuit for the coil within the ASD relay is controlled by the Powertrain Control Module (PCM). The PCM operates the ASD relay by switch- ing its ground circuit on and off. The ASD relay will be shut–down, meaning the Fig. 2 ASD and Fuel Pump Relay Terminals—Type 2 12–volt power supply to the ASD relay will be de-ac- TERMINAL LEGEND tivated by the PCM if: NUMBER IDENTIFICATION ² the ignition key is left in the ON position. This is if the engine has not been running for approxi- 30 COMMON FEED 85 COIL GROUND mately 1.8 seconds. 86 COIL BATTERY ² there is a crankshaft position sensor signal to 87 NORMALLY OPEN the PCM that is lower than pre-determined values. 87A NORMALLY CLOSED DIAGNOSIS AND TESTING - ASD AND FUEL voltage is not supplied to the rest of the circuit. Ter- minal 87A is the center terminal on the relay. PUMP RELAYS ² When the PCM energizes the ASD and fuel The following description of operation and pump relays, terminal 87 connects to terminal 30. tests apply only to the Automatic Shutdown This is the On position. Terminal 87 supplies voltage (ASD) and fuel pump relays. The terminals on the to the rest of the circuit. bottom of each relay are numbered. Two different The following procedure applies to the ASD and types of relays may be used, (Fig. 1) or (Fig. 2). fuel pump relays. ² Terminal number 30 is connected to battery volt- (1) Remove relay from connector before testing. age. For both the ASD and fuel pump relays, termi- (2) With the relay removed from the vehicle, use nal 30 is connected to battery voltage at all times. an ohmmeter to check the resistance between termi- ² The PCM grounds the coil side of the relay nals 85 and 86. The resistance should be 75 ohms +/- through terminal number 85. 5 ohms. ² Terminal number 86 supplies voltage to the coil (3) Connect the ohmmeter between terminals 30 side of the relay. and 87A. The ohmmeter should show continuity ² When the PCM de-energizes the ASD and fuel between terminals 30 and 87A. pump relays, terminal number 87A connects to termi- nal 30. This is the Off position. In the off position, TJ IGNITION CONTROL 8I - 5 AUTO SHUT DOWN RELAY (Continued) (4) Connect the ohmmeter between terminals 87 (4) Check for pin height (pin height should be the and 30. The ohmmeter should not show continuity at same for all terminals within the PDC connector). this time. Repair if necessary before installing relay. (5) Connect one end of a jumper wire (16 gauge or smaller) to relay terminal 85. Connect the other end INSTALLATION of the jumper wire to the ground side of a 12 volt The ASD relay is located in the Power Distribution power source. Center (PDC) (Fig. 3). Refer to label on PDC cover (6) Connect one end of another jumper wire (16 for relay location. gauge or smaller) to the power side of the 12 volt (1) Install relay to PDC. power source. Do not attach the other end of the (2) Install cover to PDC. jumper wire to the relay at this time. WARNING: DO NOT ALLOW OHMMETER TO CON- CAMSHAFT POSITION TACT TERMINALS 85 OR 86 DURING THIS TEST. SENSOR - 2.4L DAMAGE TO OHMMETER MAY RESULT. (7) Attach the other end of the jumper wire to DESCRIPTION - 2.4L relay terminal 86.