Section 4 (Anti-Lock Brake System With Traction Control System - BOSCH 5.3): Operation

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1999 Pontiac Grand Prix, 1999 Pontiac Firebird, 1999 Oldsmobile Intrigue, 1999 Chevrolet Camaro, and 1998 Pontiac Grand Prix. 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. Each wheel speed sensor constantly sends an AC voltage signal to EBTCM. This information is translated to wheel rotation speed. When EBTCM detects wheel lock-up is about to occur, it activates appropriate solenoid to pulse on and off rapidly, regulating hydraulic pressure to each wheel. At this time a slight pulsation should be felt through brake pedal, indicating ABS is working.

BRAKE warning indicator (Red) will illuminate when ignition switch is turned to START position and should go out when ignition switch is turned to ON position, provided that the parking brake is released and brake fluid level is correct. ABS indicator (Amber) and TC indicator (Amber) illuminate when ignition is turned on and goes out after about 2 seconds. If any indicator remains illuminated more than 30 seconds after vehicle is started, system malfunction is indicated. See DIAGNOSIS & TESTING.

Red BRAKE warning indicator will activate if parking brake is applied or brake fluid is low. Amber ABS indicator is controlled by 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 TC indicator is controlled by EBTCM and comes on if problem is detected with TCS. When indicator is illuminated, TCS is disabled and braking (conventional and ABS) is unaffected.