Traction Control System

The traction control system uses the ABS and PCM to limit wheel spin. When the ABS module detects a wheel spinning excessively, brake pressure to the appropriate brake caliper is modulated. This is accomplished by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module sends a message over the HS-CAN that a traction control event is taking place. When the IC receives this message, it will flash the sliding-car icon (twice per second). If the event is severe enough, the ABS module will also send a message to the PCM over the HS-CAN to assist with traction control. When the PCM receives this message, it will adjust engine timing and decrease fuel injector pulses. Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and sends another message over the HS-CAN indicating that the traction event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IC extinguishes the sliding-car icon. Once vehicle speed reaches or exceeds 100 km/h (62 mph), traction control is accomplished only through PCM intervention. Certain DTCs in the ABS module will disable the traction control system. Depending on the DTCs present, the yellow ABS warning indicator and/or the sliding-car icon will be illuminated.