Anti-Lock Brake System & Traction Control System: Operation

During normal driving and braking operations, ABS acts like a conventional braking system. The EBCM or EBTCM is located in trunk behind rear seat. Wheel speed sensors transmit a small AC voltage signal about wheel acceleration, deceleration and slip value to EBCM or EBTCM. The EBCM or EBTCM controls braking by activating and deactivating BPM valve.

The modulator valve consists of 3 rapidly switching solenoid valves, accumulator chamber and a return pump. The valves increase and decrease brake fluid pressure to each wheel (rear wheels are one circuit) to prevent wheel lock-up.

The modulator valve can supply only as much fluid pressure as applied by the driver through the master cylinder. The modulator valve alone cannot apply the brakes. A slight pulsation should be felt through brake pedal when ABS is active.

When ignition switch is turned to RUN position, Amber ANTI-LOCK and Red BRAKE warning lights on instrument panel will glow. After engine is started, lights go out with battery warning light. If ABS or BRAKE warning lights fail to go out or come on while driving, a system fault is indicated. See DIAGNOSIS & TESTING. TRACTION ACTIVE light on DIC will turn on when the traction control system is active.