Roll Stability Control (RSC)

The ABS module monitors the roll-rate sensor and existing stability control sensors and calculates if the vehicle may be approaching a situation where rollover is probable. If such a situation exists, the ABS module activates the roll stability control (RSC) system for preemptive action. When activated, the ABS module adjusts the brake torque at specific wheels in response to direct measurement of the vehicle roll motion. By adjusting brake torque, the system can reduce the cornering forces and, therefore, the total roll motion acting on the vehicle. Vehicles with RSC have an additional roll-rate sensor located within the sensor cluster and additional programming within the ABS module to help control the vehicle during sudden maneuvers.

Information from the roll-rate sensor is fed into the ABS module. The module uses information from the wheel speed sensors, throttle position sensor, steering wheel angle, the steering wheel rate of change and a yaw rate sensor that measures the change in vehicle direction. If the ABS module determines from all these inputs that conditions exist for a potential rollover, the system applies the brakes to one or more wheels and reduces engine torque to make the vehicle more stable.

When the ABS module activates the RSC system, the stability lamp in the instrument cluster will flash 2 times per second. If the RSC system is not yet initialized and is not available, the stability lamp will flash once every 2 seconds. If a fault is present in the ABS module that prohibits operation of the RSC system, the stability lamp will illuminate and SERVICE RSC NOW is displayed in the instrument cluster message center (if equipped) and a warning chime will sound.

The ABS module also constantly monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering input and brake application with that of the actual vehicle motion. The RSC system does not activate when the vehicle is traveling in reverse; however, the ABS and traction assist systems continue to function as usual.

When the ABS module activates the RSC system, any of the following can occur:

• A rumble or grinding sound much like the ABS or traction assist.
• A small reduction in the acceleration or speed of the vehicle.
• The stability assist indicator flashes.
• If the driver's foot is on the brake pedal, a vibration is felt in the pedal much like the ABS.