Anti-Lock Brake System: Description

Anti-Lock Brake System (ABS) consists of wheel sensors on both front rotors and in rear axle, an Electronic Control Unit (ECU) under left side of instrument panel, and a hydraulic modulator in engine compartment. See Fig 1 . Hydraulic modulator consists of valve relay, pump motor relay, connector, pump and motor, and 3 valves. See Fig 2 .

An ABS warning light in instrument panel will remain illuminated if an ABS failure occurs. If an ABS malfunction occurs, conventional braking system takes over. Vehicle may be safely driven when ABS warning light is on.

Fig 1: Locating ABS Components

Courtesy of VOLVO CARS OF NORTH AMERICA

Fig 2: Locating Hydraulic Modulator Components

Courtesy of VOLVO CARS OF NORTH AMERICA