Anti-Lock Brake System: Operation

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