Electronic Stability Control (ESC) System

The ESC system is controlled by the ABS module and uses the same wheel speed sensors and tone rings that are used for anti-lock braking. The ESC system also uses input from the steering wheel rotation sensor and the stability control sensors (yaw rate, roll rate, longitudinal acceleration and lateral acceleration), which are internal to the Restraints Control Module (RCM). Additional information from other modules is sent over the HS-CAN bus to help maintain vehicle stability.

The ABS module uses the various sensors to continuously monitor vehicle direction of travel relative to the driver's intended course. If the ABS module determines from all these inputs that the vehicle is unable to travel in the intended direction, it 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 bus that a stability event is taking place. When the IPC receives this message, it will flash the sliding-car icon. Under certain conditions during a stability event, the PCM may be requested to reduce engine torque as it does for traction control. Once the stability condition has been corrected, the ABS module 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.

Certain DTCs being present in the ABS module may disable the ESC system. Depending on the DTCs present, the yellow ABS warning indicator and/or the sliding-car icon will be illuminated.