Anti-Lock Brake System: Operation

As vehicle is moving, speed sensors send an AC voltage signal to ABS control unit. Control unit monitors brakelight switch to determine when brake pedal is pressed. When brake pedal is pressed, ABS control unit monitors signals from each speed sensor to determine rate of deceleration.

If rate of deceleration from any speed sensor reaches a preprogrammed rate, ABS control unit activates solenoid valves inside actuator. Solenoid valves are cycled to apply, release, or maintain hydraulic pressure to each wheel in any combination.

Regulating hydraulic pressure to each circuit prevents wheel lock-up. When brake pedal is released, ABS control unit deactivates solenoid valves, returning brake system to conventional mode until ABS is needed.ABS will not operate when vehicle speed is less than 6 MPH.

If ABS control unit detects a fault, ABS warning light on the instrument cluster comes on. If a malfunction occurs in system, anti-lock feature will not function, but conventional brakes will continue to operate normally.