Traction Control System
The traction control system utilizes the ABS and the PCM to minimize wheel spin during acceleration. When the ABS module detects a wheel spinning excessively, it commands the HCU to modulate brake pressure to the appropriate brake caliper. This is accomplished by opening and closing the appropriate solenoid valves inside of 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 IPC receives this message, it flashes the stability/traction control indicator (sliding car icon). If the event is severe enough, the ABS module sends a message to the PCM over the HS-CAN to assist with traction control. When the PCM receives this message, it adjusts engine timing and decreases 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 IPC turns off the sliding car icon.
Once vehicle speed reaches or exceeds 144 km/h (89 mph), traction control is accomplished only through PCM intervention.
Certain DTCs in the ABS module disable the traction control system. Depending on the DTCs present, the red brake warning light, the yellow ABS warning indicator and the sliding car icon illuminate.