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. ABS Electronic Control Module (ECM) monitors wheel speed. If any wheel slows too quickly (approaches lock-up) during brake actuation, ABS ECM will signal modulator assembly to reduce hydraulic pressure to that wheel to prevent lock-up.
ABS system consists of wheel speed sensors, sensor rotors (tone wheels), ABS warning light, ABS ECM, ABS modulator and modulator sub-assemblies. See Fig 1.
NOTE:
For information on non-ABS brake components, see DISC & DRUM
article.