Anti-Lock Brake System: Description

CAUTION: See ANTI-LOCK BRAKE SAFETY PRECAUTIONS article in GENERAL INFORMATION.

Anti-Lock Brake System (ABS) consists of hydraulic unit, actuator, solenoids, pump motor, ABS Electronic Control Unit (ECU), relays, deceleration sensor and wheel speed sensors. See Fig 1.

An ABS warning light is located on instrument cluster. ABS warning light illuminates for 3 seconds as a bulb test when ignition is turned on. A primary check is performed after each engine start and when initial vehicle speed exceeds 6 MPH. An actuator noise is heard as vehicle is started or as speed exceeds 6 MPH. This is normal operation. Anti-lock systems remains active until vehicle speed drops to less than 3 MPH.

Fig 1: Locating ABS Components

NOTE: For additional brake system information, see appropriate DISC & DRUM article.