Antilock Brakes / Traction Control Systems: Description and Operation

Anti-Lock 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) (Roll Stability Control) and traction control systems)

- Steering Column Control Module (SCCM) (contains the steering angle and rotation sensors)

- Restraints Control Module (RCM) (yaw rate, lateral and longitudinal accelerometers)

- Front wheel speed sensors

- Front wheel speed sensor tone rings (integral to the halfshafts)

- Rear wheel speed sensors

- Rear wheel bearing magnetic strips 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 (Hydraulic Control Unit))

- Brake fluid level switch

The ABS prevents wheel lock-up by monitoring the wheel speed sensors and actuating the valves in the HCU (Hydraulic Control Unit) 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) (Roll Stability Control) 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 sensors in the RCM (Restraints Control Module) to assist in stabilizing the vehicle during abrupt maneuvers.