Roll Stability Control™

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the wheel speed sensor input, throttle position input, steering wheel input and the roll 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  , the PCM sends the throttle position sensor information over the HS-CAN  and the RCM sends roll rate sensor information to the ABS module over a private HS-CAN  . The wheel speed sensor information comes directly from the ABS wheel speed sensors.

If the ABS module determines from the inputs that the vehicle is becoming unstable, 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 stability 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). By adjusting brake and engine torque the system can reduce the cornering forces and, therefore, the total roll movement acting on the vehicle. 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 RSC function does not operate with the transmission in REVERSE. The ABS module disables the RSC 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, SCCM, PCM or the RCM, the RSC function is disabled. When the RSC 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).