What does ABS lock-up mean?

[StAriel]

When the ABS light is displayed on a vehicle, it indicates a malfunction in the Anti-lock Braking System. During emergency braking, if the wheels lock up, the vehicle may lose control and skid, making it difficult for the driver to decelerate or adjust the vehicle's trajectory, posing significant safety risks. There are several scenarios in which the ABS warning light may illuminate, each with different causes and solutions, as detailed below: Scenario 1: ABS warning light remains constantly on (most common). Cause 1: The ABS wheel speed sensor's sensing area is covered by dirt, mud, or other contaminants, affecting its ability to detect the corresponding speed signal. This prevents the ABS computer from determining the vehicle speed and calculating the wheel slip rate, thus failing to issue appropriate commands to adjust braking. Solution: Clean the contaminants from the wheel speed sensor and adjust the gap between the sensor and the signal ring to restore normal function. Cause 2: Poor signal transmission due to loose connections in the system wiring or poor contact in the ABS relay, leading to system malfunction. Solution: Inspect wiring connections and re-secure any loose connections. Scenario 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple vehicle electrical components are in use, the battery voltage may drop below 10.5V. As engine speed increases and voltage rises, the ABS warning light turns off. This can also occur if the ABS system's power supply voltage is too low due to poor terminal contact or grounding issues. Solution: Check the battery's specific gravity; inspect the charging system; examine the power supply (e.g., voltage relay or poor power contact). Scenario 3: ABS warning light remains on after engine start and only turns off when the engine is turned off (IGFF). Cause: Poor grounding contact in the ABS hydraulic valve body; poor electrical connector contact in the ABS hydraulic valve body; ABS computer malfunction. Solution: Loosen and then re-tighten the grounding screw on the hydraulic valve body, cleaning the contact surface if necessary; check for enlarged connector gaps; replace the ABS or ABS/ASR computer if needed. Scenario 4: ABS warning light illuminates during high-speed driving. Cause: At high speeds, the ABS computer detects a significant discrepancy between rear and front wheel speed signals; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's tire and wheel rim specifications, typically listed on the sticker near the fuel tank cap. Scenario 5: ABS warning light intermittently illuminates. Cause: Improper adjustment of the brake light switch; poor internal contact in the brake light. Solution: With the engine running, press the brake pedal and use a finger to push the brake switch linkage fully downward, then release the brake pedal to complete self-positioning; replace the brake light switch if necessary.

[MollyRose]

I've encountered ABS lock-up issues quite a few times. Simply put, ABS (Anti-lock Braking System) is designed to prevent wheel lock-up during braking, allowing you to steer and avoid losing control. However, when the system malfunctions—such as sensors getting clogged with mud or control unit failures—the ABS stops working. As a result, pressing the brake pedal causes the wheels to lock up completely, making the car prone to skidding or spinning, which is extremely dangerous. My advice is to avoid driving too fast. If you notice the ABS warning light or feel unusually stiff brakes, head to a professional repair shop immediately to prevent accidents at high speeds. During regular maintenance, make sure to clean around the wheel speed sensors and have a mechanic test the pump and wiring periodically to minimize such failures. Remember, safety comes first—never ignore even minor issues.