Electronic Shift Control Electronic Controlled Transmissions

Electronic Shift Control

Electronic Controlled Transmissions

Modern transmissions are hydraulically operated with electronic controls. These controls provide: •A better correlation between the engine and transmission •Improved shift timing control •Improved shift quality control •Ability to provide driver-selected economy or performance operation •Improved ability to determine proper transmission operation

1 Control System

5 6 1112 8 10 7 PCM An electronic control system has three major portions: 1. The inputs provide DLC needed information. 9 2. The controller D 41 A processes information C 2 B 3 and activates the Sensors: Electronic Transaxle outputs. 1-5 Trans. Controllers Mounted 6-12 Eng. Solenoids: PCM & DLC 3. The outputs do the A-D, MIL: 9 work. INPUTS OUTPUTS 3

Electronic Valve Body

Vehicle Speed Sensor Lockup Solenoid

Shift Solenoids Pressure Control A & B Solenoid, EPC Pressure Switch Manifold External Harness Internal Harness

The internal harness transfers signals between the valve body and the controller. The section of the external harness is a repair part for the connector. The vehicle speed sensor is mounted outside of the transmission

2 Inputs

Inputs Outputs

Inputs are electrical signals TPS that provide information to Baro/MAP MLPS the powertrain control TFT module (PCM) or ECT PCM/ Eng. RPM TCM transmission control module TISS (TCM). Inputs are VSS PSM transmission, engine, and BOO vehicle sensors or switches. A/C on/off Econ-Pwr Diag. Req.

Transmission Mounted Inputs

Some inputs/sensors like the manual lever position sensor (MLPS) (A) and output speed sensor (B) are mounted on the outside of the transmission. Others sensors are mounted internally.

A B 6

3 VSS

The vehicle speed sensor (VSS) provides a Speed Sensor Rotor transmission output shaft speed signal. The VSS signal performs the same job as a governor in a hydraulic- controlled transmission. The VSS signal is also used for the vehicle's speedometer Speed and other speed-related Sensor functions.

VSS Operation

Magnetic Core Most VSS are a coil of wire around a magnetic core. Coil AC The VSS is mounted close to Magnetic Volts AC a reluctor that has gear-like lines of Volts flux at teeth. When the reluctor rest rotates, the teeth pull the magnetic lines of force over the coils of wire in the Reluctor sensor.

4 VSS Operation +5V Magnetic Core Coil AC 0V +5V The reluctor rotation Magnetic Volts lines of AC 0V generates an AC voltage flux at Volts -5V rest -5V with a frequency relative to Reluctor reluctor speed (Top Right). Note that current direction changes with the tooth ACAC AC moving toward or away VoltsVolts Volts from the sensor core. Magnetic lines of Magnetic lines of flux being pulled flux being pulled out into core of core

Animation: VSS Operation 9

Analog to Digital

VSS Signal Converter Signal to ECM

Digital Signal Analog Signal

An analog signal, like that from the previous VSS, has a variable voltage. A digital signal is a series of on-off electrical pulses. Some ECMs require a converter to change analog signals into digital signals.

5 MLPS

Input Speed Sensor Manual lever position Output Speed Sensor switch (MLPS) is mounted onto the manual shift linkage entering the transmission. Shift linkage movement operates the MLPS. Note that this transaxle has two speed sensors. Manual Lever Position Switch (MLPS) 11

MLPS Operation Powertrain Control Transmission Module (PCM) Control Module This MLPS is a group of (TCM) four switches. Moving the shift lever will open or close Starter Relay the switch contacts, and the signal transfers that B/U information to the TCM. Lamp Note that the MLPS also works with the starter relay and the backup lamp.

Manual Lever Position Switch (MLPS) Animation: MLPS 12

6 MLPS Wire Connections ECM

Trans. Range Signal

5V Reference MLPS Sensor Ground Some MLPS use a separate wire for each gear range (previous slide). Others use a pair of wires with a block of resistors. The ECM monitors the return voltage to determine the gear range.

Pressure Switch Switch Manifold Lo Ind. PRND43 Switch Rev. Indicator Ind. Switch This transmission uses Switch five pressure switches mounted on a special manifold. Each switch has a set of contacts that are closed when PRND4 Ind. Drive Ind. fluid pressure acting on Switch Switch a diaphragm pushes Switch Fluid O-Ring them together. Diaphragm

Contacts 14

7 TFT Sensor

Transmission fluid temperature (TFT) sensors are placed into the ATF. It is a thermister; a variable resistor with a negative temperature coefficient. The resistance decreases as the fluid Transmission Fluid temperature increases. Temperature (TFT) Sensor Animation: Transmission Temperature Sensor 15

Internal Harness

This transmission uses a twelve pin connector to connect the internal harness to the external electrical harness on Transmission the vehicle. Note the identification on the connector pins. Connector

8 Harness Connector Connector Internal Pressure Switch Harness Manifold Solenoid A Variable Force Solenoid PWM Solenoid Solenoid B Temperature Sensor

The internal harness contains the wires to connect the sensors and solenoids to the connector at the side of the transmission.

Driving Pattern Select Switch

This switch is also called Economy the Power-Economy switch. Power It allows the driver to select one of two or more driving modes. The power mode will have higher shift points From and torque converter clutch Battery (TCC) lockup. Driving Pattern Ind. Lamp Select Switch

9 OD Cancel Switch

OD Cancel OFF Switch This switch cancels overdrive ON (OD) range and limits transmission operation to 1-2 and 2-3 operation only.

OD OFF Ignition Switch Lamp TCM

OD Cancel Switch

Engine Mounted Inputs

Man. Absolute Engine Speed Pressure (MAP) (Ig. Module) Powertrain Control Module Throttle (PCM) These engine and Position body mounted Sensor sensors are used (MAP) for both engine and transmission control. They have a definite affect on Brake Switch transmission Engine operation. Coolant Air Conditioning Temperature (A/C) Switch Cruise Control Sensor (ECT) Information 20

10 TPS

Throttle Position Powertrain Sensor (TPS) Control Module The throttle position sensor (PCM) (TPS) is a major engine control sensor. It is mounted at the fuel injector or carburetor. The TPS signal to the transmission controller performs the same function as the throttle valve on a hydraulic-controlled transmission. Accelerator Pedal

Animation: Throttle Position Sensor 21

ECT Sensor

The engine coolant temperature, ECT, sensor lets the ECM know if the engine coolant is too cold, at operating temperature, or approaching an overheat condition.

Upper Radiator ECT Sensor Hose

Animation: ECT Sensor 22

11 Controllers

This transmission control module (TCM) has a multi-pin connector for the wiring harness. The TCM notes changes in engine and transmission operation and produces the proper output signal so the transmission can adapt to those changes.

Bus Communication

Powertrain Control Module (PCM)

Body Transmission Control Control Module Electronic Shift Module (TCM) Indicator Display (BCM)

The control modules can share input and output information through a Bus/Multiplex Link. Two wires, normally twisted, connect two or more control modules. This feature greatly reduces the amount of wires in a vehicle.

12 Engine Transmission Coordination

Reduce Torque When this transmission Torque Reduced PCM TCM is ready for an upshift, Shift Complete the transmission Cut Fuel Retard Timing Shift controller (TCM) signals Instruction the engine controller (PCM) to reduce torque/ power. Normal engine operation resumes after the shift. This feature increases transmission life because of the reduced torque loads during upshifts. 25

Shift Quality

TCM TCM Input Speed Output Speed Sensor Sensor Input:Input: 1,500 1500 rpm rpm Input Shaft Speed: Output: 500 rpm Output Shaft Speed: 1,500 rpm Output: 500 rpm 500 rpm GearGear Ratio: Ratio: 3:1 3:1

Planetary Gearset The TCM compares the speed of the two speed sensors. It can calculate the gear ratio and the time it took for the transmission to complete the ratio change. From this, the TCM can determine if the shift took the proper amount of time. 26

13 Shift Quality

If the shift took too much time, the TCM can increase fluid pressures for future shifts. The TCM can reduce pressure if the shift was too fast and harsh. It can also determine if the transmission is slipping internally, and in this case, it will turn on the MIL, Malfunction Indicator Light.

Outputs

Transmission outputs include: •Shift solenoids •Pressure control solenoids •Torque converter clutch solenoids •Shift indicator lights •Malfunction indicator lamps (MIL)

14 Shift Solenoids

Filter Coil Windings Screen A solenoid has a coil of wires that becomes a magnet when current flows through the windings. When magnetized, the plunger will move to the right and allow the metering O-Ring ball to move off its seat. This Metering Ball will allow fluid to flow Spring through the filter screen and Plunger out the exhaust. Electrical Connector

Animation: Shift Solenoid 29

Solenoid B+ & Ground

Fuse A one-wire solenoid is ECM ECM connected directly to ground Controls B+ by its mount and switched to B+ by the ECM to turn it on. Most two-wire solenoids are connected to B+ through a Fuses fuse and the ECM controls the ground to turn it off or on. ECM Controls Ground

15 Shift Solenoid Operation

Drive 1-2 Signal These shift solenoids 1-2 Shift control the pressure at Solenoid one end of a shift valve. 1-2 Shift Valve ON The upper solenoid 2-3 Drive 3-4 Drive (normally open) is on so it 2-3 Shift is blocking fluid flow, and Solenoid 2-3 Shift Valve EX OFF the pressure is keeping 2-3 Signal the shift valve to the left. The lower solenoid is off so fluid pressure escapes to the exhaust. The spring (at the left end) has moved the valve to the right. Animation: Shift Solenoid Operation 31

Direct Solenoid Operation

In this transmission, the solenoid stems (yellow) act on the check ball/ Solenoid OFF Solenoid ON valve. The taper on the

stems opens or closes a Vent Open Vent Closed vent. When the solenoid is

off, the stem is upward, Valve Closed Valve Open opening the vent and closing the valve. Manual Valve

Animation: Shift Solenoid Operation 2 32

16 50% Duty One Duty Cycle Cycle Cycle

ON Duty Cycle tells us how much of OFF the time the solenoid is turned on. Fluid pressure control solenoids are 25% either cycled or partially applied to ON Duty produce a specific pressure. OFF Cycle Many shift solenoids are either on or off. Some shift solenoids are ON 75% cycled to vary the apply rate (fluid Duty OFF pressure increase). Cycle

PWM Solenoids

Solenoid ON Control Logic: OFF Driver Pulse ON Logic: OFF Full On Hold In Pulse Duty Cycle Solenoid Voltage: 0 Inductive Current Flow Inductive Path Opened Solenoid Current: 0

Pulse width modulation (PWM) turns the solenoid on and off at a specific pulse width or rate (Duty Cycle). Some PWM solenoids are cycled at 3 Hz (3,000 times per second).

Animation: PWM Solenoid 34

17 Fluid Pressure Control

Increasing the current flow to this pressure control solenoid/force motor will reduce line pressure. No current flow produces the highest pressure for the firmest or strongest shifts.

TCC Apply

Clutch Modern torque converter Plate clutches, TCC, apply the clutch Turbine to reduce slippage, reduce Impeller Stator emissions, and improve fuel mileage. TCC application is commonly controlled using a Hub solenoid.

Animation: TCC Operation 36

18 TCC Control

PWM Solenoid Duty Cycle TCC Fully Applied

This solenoid is cycled at CD a 25 to 50% duty cycle during torque converter TCC Apply TCC Release Rate E Rate clutch (TCC) apply. This B produces a much F TCC Apply A smoother TCC apply and Pressure release.

Time

MIL

On this vehicle, the OD cancel lamp (OD OFF) also serves as the malfunction indicator lamp (MIL). A transmission problem is indicated if this light is flashing.

OD Cancel Lamp 38