Automatic Transmission (V12) ~ Pow. rtrain
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.
2. During gearshifts, to request reduction of engine torque
3. During fault conditions, to inform the ECM.
During normal operation
theTCM 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 recognise 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 afault is detected bytheTCM 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.
8.2.5 DIAGNOSTIC LINKS
Diagnostic
L line
One of a two wire interface used to activate stored diagnostic codes for reading by external equipment.
Diagnostic K Line
One of a two-wire interface used to communicate stored diagnostic codes for reading by external diagnostic equip- ment.
X300 EDM 7 Issue 1 August 1994
