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. The ABS Electronic Control Module (ECM) monitors wheel speed. If any wheel slows too quickly (approaches lock-up) during brake actuation, ECM will signal modulator assembly to reduce pressure to that wheel to prevent lock-up.

ABS system consists of Wheel Speed (W/S) sensors, sensor rotors (tone wheels), ABS warning light, ABS Electronic Control Module, ABS modulator and modulator sub-assemblies. See Figure .