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 sensor messages and the yaw rate sensor messages with the actual vehicle motion. The ABS module receives the steering wheel sensor messages from the PSCM (vehicles not equipped with active park assist) or SCCM (vehicles equipped with active park assist) and the yaw rate sensor messages from the RCM, all messages are sent directly to the ABS module along the HS-CAN 2. If the ABS module determines from the inputs the vehicle is unable to travel in the intended direction, it modulates the brake pressure to the appropriate brake caliper(s) 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 calculates how much engine torque reduction is required to reduce vehicle speed to help stabilize the vehicle and sends this torque reduction message, along with an ESC event message, to the GWM over the HS-CAN 2. The GWM sends the torque reduction message to the PCM over the HS-CAN 1 and the ESC event message to the IPC over the HS-CAN 3. When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. 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 stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

ESC does not operate with the transmission in REVERSE. ESC is disabled if there is a wheel speed sensor, stability sensor or steering angle sensor DTC present in the ABS module. ESC is also disabled if there is a communication error between the ABS module and the PSCM, the ABS module and the SCCM or the ABS module and the RCM. When ESC is disabled, the ABS module sends a message to the GWM along the HS-CAN 2 which gateways the message to the IPC over the along the HS-CAN 3 to illuminate the stability-traction control OFF indicator (sliding car OFF icon).