Aurora V8-4.0L VIN C (1996)
Powertrain Control Module: Description and Operation
Traction Control
DESCRIPTION
Traction Control is a function of the PCM and the EBTCM that reduces front wheel slip during acceleration by applying the front brakes and reducing
engine power.
OPERATION
The PCM continuously sends out a PWM signal that indicates the torque output of the powertrain. This signal, referred to as the Delivered Torque
signal, is used by the EBTCM to determine what action is required when it sees the front wheels slipping. The EBTCM may decide to apply the front
brakes only or apply the front brakes and request reduced torque output from the powertrain. The EBTCM requests reduced torque using another
PWM signal. This signal, referred to as the Desired Torque signal, is used by the PCM to determine it the EBTCM is requesting reduced torque output
from the powertrain. If the EBTCM requests reduced torque, the PCM will disable between one and seven fuel injectors to achieve this.
Desired Torque will normally be a 90 percent duty cycle signal to the PCM. When the EBTCM decides to request reduced engine power, it decreases
the duty cycle of the Desired Torque signal by the amount of torque reduction required (90 percent duty cycle means no torque reduction, 10 percent
duty cycle means 100% torque reduction). The PCM responds by shutting off fuel to one or more cylinders depending on the percent torque reduction
requested. The PCM will not shut off any fuel injectors if any of the following conditions are present
^
Coolant temperature is below -40°C (40°F) or above 131°C (268°F).
^
A low coolant level is present.
^
Engine speed is below 600 rpm
The disabled fuel injectors will be re-enabled one by one as the need for traction control ends.
Several DTC(s) disable traction control when set. They will also trigger a TRACTION OFF light or message. The PCM traction control override also
disables traction control and triggers the message. To diagnose a Traction Off light/message, diagnose any DTC(s) set first. Then check the traction
control override and, if active, deactivate the override.
