Antilock Brakes / Traction Control Systems: Description and Operation

Anti-Lock Control

Anti-Lock Brake System (ABS)
The ABS consists of the following components:
^ ABS module
^ Hydraulic control unit (HCU)
^ Front wheel speed sensor
^ Front wheel speed sensor ring
^ Rear axle speed sensor
^ Rear axle speed sensor ring (integral to the differential case)

The ABS prevents wheel lockup by monitoring the wheel speed sensors and actuating the HCU, modulating 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 engine only traction control (EOTC) system utilizes the PCM to prevent wheel spin and help maintain vehicle control during acceleration. This system functions by obtaining wheel speed information from the ABS and modulating engine torque by regulating fuel and spark.

The rear axle speed sensor ring is attached to the differential case. It is necessary to remove the ring gear in order to remove the rear axle speed sensor ring.