Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Anti-Lock Brake System: Operation
During normal driving and braking operations, ABS acts like a conventional braking system. Each wheel sensor constantly sends an AC voltage signal to Electronic Brake Control Module (EBCM). This information is translated to wheel rotation speed. When EBCM detects wheel lock-up is about to occur, it activates appropriate solenoid to pulse on and off rapidly, regulating hydraulic pressure to each wheel. A slight pulsation should be felt through brake pedal, indicating ABS is working.
BRAKE warning indicator will come on when ignition switch is turned to START position and should go off when ignition switch is turned to ON position. ANTI-LOCK indicator comes on when ignition is turned on and goes out after approximately 2 seconds. If either indicator stays on 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 ANTI-LOCK indicator is controlled by EBCM and comes on if problem is detected with ABS. When indicator is on, ABS is disabled and braking is accomplished by conventional brake system. If both warning indicators are on, check conventional brake system for hydraulic system failure.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.