Section 194 (Anti-Lock Brake System): Description

WARNING: This page is about a different car, the 2003 Toyota Prius, 2002 Toyota Prius, and 2001 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

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 and wheel speed sensors. See Fig 1. An ABS warning light and Brake warning light are located in instrument cluster. ABS ECU performs a bulb test by illuminating ABS warning light and Brake 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: Identifying ABS System Components

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