What is ABS Lock-Up?
3 Answers
The following are the fault diagnosis and troubleshooting for automotive ABS brake lock-up: 1. ABS regulator power circuit failure, troubleshoot the ABS regulator power circuit. 2. Battery voltage too low, replace the battery or repair the charging system fault. 3. ABS indicator light or wiring fault, replace the combination meter or troubleshoot the ABS indicator light. 4. ABS wheel speed sensor, ABS tone ring, or ABS solenoid valve failure, repair or replace the ABS wheel speed sensor, ABS tone ring, or ABS regulator. 5. ABS control unit failure, replace or repair.
ABS lock-up means there's a malfunction in the anti-lock braking system. Normally during hard braking, the ABS makes a clicking sound and prevents the wheels from completely locking up to avoid skidding. But if the sensor fails, the system can't detect wheel speed changes and may lock the wheels directly. Hydraulic transmission issues like oil leaks in the lines or blocked valve bodies can also cause stiff brake pedals. Last time this happened to my car in the rain, the tires left black skid marks and the steering wheel became immovable. The dealership found the left front wheel speed sensor was clogged with mud - cleaning it and replacing the brake fluid fixed the issue. Don't ignore such problems, especially in snowy conditions when losing ABS can easily cause skidding into guardrails.
Last month I encountered an issue with ABS lock-up. While driving, I suddenly felt the brakes become heavier and heard a clunking sound from the tires. Then I noticed the ABS warning light illuminated yellow on the dashboard. The mechanic said there are three common causes: metal debris clogging the wheel speed sensor can cause signal errors, a burnt circuit board in the ABS pump can lead to loss of regulation capability, and brake fluid containing over 3% water can also cause system failure. It's recommended to check the sensor position every 20,000 kilometers, change the brake fluid regularly, and avoid using high-pressure water jets directly on the wheel hub center when washing the car. If you notice severe brake pedal vibration at traffic lights, it's best to drive straight for inspection.
