Traction Control

Traction control is a function of the PCM and Electronic Brake And Traction Control Module (EBCM) to reduce wheel slip during acceleration. When wheel slip is detected, the EBCM applies the front brakes, and the PCM reduces engine power. The PCM continuously sends the EBCM a Pulse Width Modulation (PWM) signal to indicate the torque output of the powertrain. This signal, referred to as the delivered torque signal, is used by the EBCM to determine the required action when it sees the front wheels slipping. The EBCM may decide to apply the front brakes only, or apply the front brakes and signal the PCM to reduce the torque output of the powertrain. The EBCM requests reduced torque using another PWM signal. This signal, referred to as the desired torque signal, is used by the PCM to determine the amount of torque reduction requested by the EBTCM. The PCM adjusts the ignition timing in response to the desired torque signal.

The desired torque signal varies within a range of 95 percent and 5 percent duty cycle. A duty cycle at 95 percent indicates no torque reduction. A duty cycle at 10 percent indicates full torque reduction. The desired torque signal to the PCM will normally be at a 90 percent duty cycle. The EBCM will decrease the duty cycle of the signal by the amount of torque reduction desired. The PCM responds to the signal by adjusting the ignition timing. The PCM may shut OFF the fuel to one or more cylinders unless the following conditions are present:
^ The coolant temperature is below -40°C to (-40°F) or above +131°C to (+268°F).
^ A low coolant level is present.
^ The engine speed is below 600 RPM.

The PCM will re-enable the fuel injectors as the need for traction control ends.

Traction control will be disable when certain DTCs set. The PCM will request a TRACTION OFF light/message via class 2 serial data when the DTCs set.