Anti-Lock Brake System: Operation

Each wheel sensor sends an AC electrical signal to ABS ECU. The ABS ECU translates this information as wheel speed. When any decelerating wheel speed rate is determined to be excessive in comparison to other monitored wheels, the hydraulic unit cycles hydraulic brake pressure to each wheel to equalize speed of all wheels. ABS turns itself off when vehicle speed drops to 4 MPH. Minor lock-up may occur at this point.

With engine running and vehicle speed more than 4 MPH, pump motor will operate for a short period of time and may be heard inside vehicle. During pump motor operation, ABS system is completing a self-check. During ABS system operation, a pulsing brake pedal and vibration in steering wheel and vehicle body may be experienced. These conditions are normal.