Section 2 (Anti-Lock Brake System - With TCS): Operation: Abs

WARNING: This page is about a different car, the 1996 Subaru Legacy and 1995 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.

As vehicle is driven, each wheel speed sensor sends an AC signal to ABS/TCS control unit. As brake pedal is depressed, ABS/TCS control unit starts to monitor vehicle rate of deceleration. If rate of deceleration is greater than preprogrammed amount, ABS/TCS control unit signals hydraulic control unit solenoid valves to regulate brake hydraulic pressure. Solenoid valves increase or decrease hydraulic pressure to each front wheel and/or to both rear wheels. This action will slow each wheel at a preprogrammed rate to prevent wheel lock-up, allowing driver to maintain steering control.

If ABS malfunction occurs, ABS warning light in instrument cluster panel will come on. ABS/TCS control unit will then deactivate ABS system, leaving conventional braking system intact. ABS/TCS control unit can also self-diagnose ABS during each ignition cycle (OFF-ON-OFF). If an ABS fault is detected, ABS/TCS control unit will store a trouble code to assist technician in diagnosing ABS.