Anti-Lock Brake System: Description

The Anti-Lock Brake System (ABS) keeps wheels from locking up under extreme braking conditions. ABS prevents excessive wheel slip by pulsing modulation of brake pressure. Hydraulic and Electronic Control Unit (HECU) monitors wheel speed. If any wheel slows too quickly (approaches lock-up) during brake actuation, HECU will reduce pressure to that wheel to prevent lock-up.

ABS system consists of wheel speed sensors, sensor rotors (tone wheels), ABS warning light and HECU. See Figure .