Initial Inspection and Diagnostic Overview
INPUTS:Transmission Range
The transmission range is detected by the pressure switch manifold located within the transmission unit. The manifold transmits a coded message to the TCM indicating gear selector position.
Performance Mode Select
Performance mode select uses a two wire input to the TCM allowing selection of different transmission operating modes.
Line A; Used for selection of traction control shift pattern and controlled by the ABS/TC CM.
Line B; Used for selection of "Normal" or "Sports" mode, manually selected at a two position rocker switch mounted on the gear selector unit. Switch resistance is equal to or greater than 100k ohms, open circuit and equal to or less than 0.5 ohms closed circuit, measured across contacts at a current of 10mA.
Kick-down Switch
This signal is control led by the operation of the kickdown switch on depression of the accelerator pedal to its full extent. The switch remains in "normally open" position until contact with the pedal closes the contacts. Switch resistance is equal to or greater than 100k ohms, open circuit, and equal to or less than 0.5 ohms closed circuit, measured across contacts at a current of 10mA.
Calibration Select
Allows different calibration selection for different markets to accommodate variation in fuel (especially Russian and South American).
When calibration select is used only one part number per engine variant is required. Where this facility is not used the shorting plug to ground must not be fitted.
Engine Speed
The engine speed is provided by an open collector signal supplied from the engine management control module (ECM).
Throttle Position
This signal, from the ECM, performs the following two functions:
1. To convey throttle position information to the TCM.
2. To indicate fault conditions between ECM and throttle potentiometer.
Engine Torque (and warm-up)
This signal, from the ECM, performs the following three functions:
1. During cranking to convey the completion of an engine warm-up cycle to TCM.
2. To convey engine torque information, under normal running conditions, to TCM.
3. To convey engine torque fault signals to TCM.
Engine "warm-up" cycle commences from ignition ON until 500ms after the engine exceeds 400 rpm. After this time delay either an engine torque, or torque fault signal will be transmitted.
Transmission Input Speed
The transmission input speed sensor is mounted within the transmission housing and produces a variable frequency signal, directly proportional to forward clutch housing rotational speed which is transmitted to the TCM. Sensor resistance is between 1k ohm and 2k ohm.
Transmission Output Speed
The transmission output speed sensor is mounted within the transmission housing and produces a variable frequency signal, directly proportional to the rear carrier rotational speed which is transmitted to the TOM. Sensor resistance is between 1k ohm and 2k ohm.
Brake Application
When a brake application signal is received, due to brake switch operation, the torque convertor clutch lock-up solenoid is deenergized, releasing lock-up mode if already applied.
Transmission Oil Temperature
The transmission oil temperature sensor, located within the internal harness, monitors oil temperature and transmits a corresponding signal to the TCM.
OUTPUTS:
Gear Shift Solenoids
The two gear shift solenoids, located within the transmission housing, determine gear ratio when the selector is in any of the forward gear positions.
Force Motor
The force motor, mounted within the transmission housing acts as a transmission torque fluid pressure regulator.
Torque Converter Clutch (TCC) Solenoid
The torque converter clutch solenoid, mounted within the transmission housing, provides a direct drive from the engine, via the converter clutch, to the driven wheels, giving the efficiency of a manual gearbox. The solenoid has closed loop control giving a high level of refinement during engage/disengage operations.
Engine Torque Reduction and Malfunction Indication
This signal, to the ECM, has three modes of operation:
1. To indicate normal engine operation to the ECM (17% Duty Cycle).
2. During gearshifts, to request reduction of engine torque (20 - 90% Duty Cycle).
3. During fault conditions, to inform the ECM (12% Duty Cycle).
During normal operation the TCM outputs a constant duty cycle signal to the ECM. The signal is changed when torque reduction is required to indicate to the ECM the degree of ignition retardation necessary. If a fault condition, relating to OBD II CARB legislation, occurs the TCM will transmit a signal to the ECM relating this event. The ECM will only respond to this signal if its duration is 100 milli-seconds or longer.
If the signal from the torque reduction line is either HIGH or LOW for 2 or more seconds the EMS will recognize that a fault may be present and transmit this information to the TCM.
If the signal from the torque reduction line lasts for 2 or more seconds the EMS will return to normal operation.
Sport Mode Indicator Lamp
The sport mode indicator lamp, mounted on the instrument panel, is illuminate when sport mode is selected and the ignition switch is ON. Sport mode is selected at a two position switch mounted to the rear of the gear selector assembly.
Gearbox Failure Warning Lamp
The gearbox failure warning lamp, mounted on the instrument panel, is illuminated when a fault is detected by the TCM within the transmission electrical or mechanical systems.
Vehicle Speed (12 cylinder vehicles only)
This output signal is calculated from the transmission output speed and supplied to the ECM as an indication of vehicle speed.