Electronic Stability Control (ESC)

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering wheel input and the yaw rate sensor input with the actual vehicle motion. Steering wheel angle information is calculated by the PSCM and sent to the ABS module over the HS-CAN. Vehicle yaw rate information is sent to the ABS module from the RCM over a private HS-CAN. If the ABS module determines from the inputs the vehicle is unable to travel in the intended direction, the ABS module modulates brake pressure to the appropriate brake calipers 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 vehicle stability event message over the HS-CAN. When the PCM receives this message, it assists with vehicle control by adjusting engine timing and decreasing fuel injector pulses. When the IPC receives this message, it flashes the stability-traction control indicator (sliding car icon). Once the vehicle instability has been corrected, 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 bus indicating the stability event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

The ESC function does not operate with the transmission in REVERSE. The ABS module disables the ESC function if there are any wheel speed sensor, stability sensor or steering angle sensor DTCs present in the ABS module. Also, if there is a communication error between the ABS module and the PSCM or the RCM, the ESC function is disabled. When the ESC function is disabled, the ABS module sends a message over the HS-CAN to the IPC to illuminate the stability-traction control indicator (sliding car icon).