Principles of Operation

ABS with Traction Control 

The ABS module manages the anti-lock braking, while the traction control and engine control systems maintain vehicle control during deceleration and acceleration.

When the ignition switch is in the RUN position, the ABS module does a preliminary electrical check and, at approximately 6 km/h (4 mph), the hydraulic pump motor is turned ON for approximately 1-1/2 seconds. Any malfunction of the ABS module disables the system and the ABS warning indicator illuminates. However, the power-assist braking system functions normally.

The traction control system controls wheel spin by modulating engine torque and applying, then releasing, the appropriate rear brake to restore traction when driving on slippery or loose surfaces.

Electronic Brake Distribution (EBD) 

The hydraulic control unit (HCU) is used as an electronic proportioning valve for electronic brake distribution (EBD). The HCU controls the brake fluid pressure to the rear brakes to help prevent them from applying before the front brakes. If the ABS is disabled due to DTCs being present in the module, the EBD will continue to function unless there is a complete failure of the HCU. When EBD is disabled, the ABS warning indicator also illuminates.