Anti-Lock Brake System: Operation
As vehicle is moving, each wheel sensor sends an AC signal to the ABS actuator/control unit. When brake pedal is applied, ABS actuator/control unit receives signal through stoplight switch. When this occurs, ABS actuator/control unit will monitor deceleration rate of wheels through wheel speed sensors. One sensor is located on each wheel.
If deceleration rate from any speed sensor reaches a preprogrammed rate, ABS actuator/control unit activates solenoid valves (located inside control unit). Solenoid valves are cycled to apply, release or maintain hydraulic pressure to each brake caliper or wheel cylinder depending upon signals from . Regulating hydraulic pressure to each caliper prevents wheel lock-up. See Fig 1 .
When brake pedal is released, ABS actuator/control unit will deactivate solenoid valves, and system will return to conventional brake system operation until ABS is again needed.
If ABS actuator/control unit detects a fault, ANTI-LOCK warning light on the instrument cluster comes on. ABS actuator/control unit deactivates ABS when a fault is detected, but conventional brake system is not affected.