Anti-Lock Brake System: Description

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 in instrument cluster. ABS ECU performs a bulb test by illuminating ABS warning light for 3 seconds when ignition is turned on. A primary check is performed after each engine start, and when initial vehicle speed exceeds 6 MPH. Under normal operation, an actuator noise is heard as vehicle is started or as speed exceeds 6 MPH. Anti-lock system remains active until vehicle speed drops to less than 3 MPH.

Fig 1: Locating Brake System Components

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