Anti-Lock Brake System: Description: Notes
NOTE:
For information on non-ABS brake components, see appropriate DISC & DRUM article. Hydraulic and Electronic Control Unit (HECU) can also be referred to as the Anti-Lock Brake System Control Module.
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 signal modulator assembly to reduce hydraulic pressure to that wheel to prevent lock-up.
ABS system consists of wheel speed sensors, rotors with exciter rings (tone rings), ABS warning light and HECU. See Fig 1 .