Section 4 (Anti-Lock Brake System - TCS-ETS - DELPHI DBC 7): Operation

WARNING: This page is about a different car, the 1999 Buick Regal and 1999 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

During normal driving and braking operations, ABS acts like a conventional braking system. Wheel speed sensors transmit an AC voltage signal about wheel acceleration, deceleration and slip value to EBCM/EBTCM. The EBCM/EBTCM controls braking by activating and deactivating BPMV.

The modulator valve consists of rapidly switching solenoid valves, accumulator chamber and a return pump. The valves decrease brake fluid pressure to each wheel to prevent wheel lock-up.

The modulator valve can supply only as much fluid pressure as applied 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.

The Red BRAKE warning indicator and Amber ANTI-LOCK indicator will illuminate when ignition switch is turned to RUN position and should go out after a three second self-test. If any indicator remains illuminated after vehicle is started, a system malfunction is indicated. See DIAGNOSIS & TESTING .

The Red BRAKE warning indicator will activate if parking brake is applied or brake fluid is low. The Amber ANTI-LOCK indicator is controlled by EBCM or EBTCM and comes on if problem is detected with ABS. When indicator is illuminated, ABS is disabled and braking is accomplished by conventional brake system. If both warning indicators are illuminated, check conventional brake system for hydraulic system failure. Amber TRACTION OFF indicator is controlled by EBTCM and comes on if problem is detected with TCS-ETS. When the TRAC OFF indicator is illuminated, TCS-ETS is disabled and braking (conventional and ABS) is unaffected.