Anti-Lock Brake System Outline

During vehicle operation, including normal and anti-lock braking, the ABS control module monitors all electrical anti-lock functions and some hydraulic operations.
When the brakes are applied, brake fluid is sent through four normally open solenoid valves contained inside the ABS hydraulic control unit to each wheel.
If the control module senses a wheel is about to lock, it will prevent any more fluid from entering that wheel circuit.
Once the affected wheel comes back up to speed, the control module returns the valves to their normal condition allowing fluid to flow to the affected brake.
When the ignition is turned to RUN, the yellow ABS warning indicator will appear for three seconds as part of a system self-check.
A malfunction in the system will cause the control module to shut off or inhibit the system. However, normal power-assisted braking remains. Malfunctions are indicated by a yellow ABS warning indicator in the instrument cluster.