Antilock Brakes / Traction Control Systems: Description and Operation

Anti-Lock Control


ABS with Roll Stability Control (RSC(R)) and Traction Control

The ABS with Roll Stability Control (RSC(R)) and traction control consists of the following components:

- Hydraulic Control Unit (HCU)
- ABS module (also controls the RSC(R) system and traction control system)
- Stability/traction control switch
- Steering Angle Sensor Module (SASM)
- Stability control sensor cluster (contains the accelerometer[s], roll rate sensor and yaw rate sensor)
- Front wheel speed sensors
- Front wheel speed sensor tone rings (integral to the halfshafts)
- Rear wheel speed sensors
- Rear wheel speed sensor tone rings are:
- integral to the halfshaft on All-Wheel Drive (AWD) vehicles.
- integral to the wheel hub and bearing assembly on Front Wheel Drive (FWD) vehicles.

- Brake pressure transducer (integral to the HCU)
- Brake fluid level switch

The ABS prevents wheel lock-up by monitoring the wheel speed sensors and actuating the valves in the HCU which modulates the brake pressure to the brake calipers. By preventing the wheels from locking up, the driver is able to maintain steering control and stop in the shortest possible distance under most conditions. The traction control system utilizes the same components as the ABS to prevent wheel spin and help maintain vehicle control during acceleration. The RSC(R) system utilizes the same components as the ABS and the traction control systems and also monitors the steering wheel rotation sensor and the stability control sensor cluster to assist in stabilizing the vehicle during abrupt maneuvers.

The front wheel speed sensor tone rings are integral to the front halfshafts.

On AWD vehicles, the rear wheel speed sensor tone rings are integral to the rear halfshafts.

On FWD vehicles, the rear wheel speed sensor tone rings are integral to the wheel hub and bearing assembly.