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. On vehicles without active park assist, steering wheel angle information is calculated by the PSCM  and is sent to the ABS  module over the HS-CAN  . On vehicles with active park assist, steering wheel angle information is sent to the SCCM  from the steering wheel angle sensor, this information is sent to the ABS  module over the HS-CAN  . On vehicles with active park assist, the ABS  module also receives steering angle information from the PSCM  . The ABS  module compares the steering angle information received from both modules against one another. Regardless of active park assist capabilities, 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 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).