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 that of the actual vehicle motion. The SCCM (vehicles with active park assist) or PSCM (vehicles without active park assist) sends the steering wheel angle and rate of change information to the ABS module over the HS-CAN  while the RCM sends yaw rate sensor information to the ABS module over a private HS-CAN  . If the ABS module determines from the inputs that the vehicle is unable to travel in the intended direction, the ABS module modulates 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 sends a message over the HS-CAN  that a vehicle stability event is taking place. 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 that the event has ended. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the 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, the SCCM 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 both the sliding car icon and the stability/traction control disabled indicator (sliding car OFF icon).