What Causes the ABS Light on the Dashboard to Illuminate?

[OKaleb]

There are various conditions for the ABS light to illuminate, and different conditions correspond to different fault causes and solutions, as detailed below: Condition 1: The ABS warning light stays on constantly (most common). Cause 1: The ABS wheel speed sensor's sensing part is covered by dirt, mud, or other contaminants, affecting the sensor's ability to detect the corresponding wheel speed signal. This prevents the ABS computer from determining the vehicle speed and wheel slip rate, thus failing to issue appropriate commands to regulate braking. Solution: Clean the dirt from the wheel speed sensor and adjust the gap between the sensor and the signal ring to restore normal operation. Cause 2: Poor signal transmission due to loose connections between system lines or poor contact in the ABS relay, leading to system failure. Solution: Inspect the wiring connections and reconnect any loose parts. Condition 2: The ABS warning light intermittently illuminates and turns off when accelerating. Cause: When multiple vehicle electrical devices are in use, the battery voltage drops below 10.5V. As the engine speed increases, the voltage rises, causing the ABS light to turn off. Alternatively, the ABS system's power supply voltage may be too low due to poor terminal contact or grounding issues. Solution: Check the battery's specific gravity, inspect the charging system, and examine the power supply (e.g., voltage relay or poor power contact). Condition 3: The ABS warning light remains on after engine startup and only turns off when the engine is turned off (IGFF). Cause: Poor grounding contact in the ABS hydraulic valve body; loose wiring connections in the ABS hydraulic valve body; or ABS computer malfunction. Solution: Loosen and retighten the grounding screw of the hydraulic valve body, cleaning the contact surface if necessary. Check for enlarged gaps in the connectors. Replace the ABS or ABS/ASR computer if needed. Condition 4: The ABS warning light illuminates during high-speed driving. Cause: The ABS computer detects a significant discrepancy between the rear and front wheel speed signals during high-speed driving. Incorrect tire or wheel rim specifications may also be a factor. Solution: Refer to the vehicle's tire and wheel rim specifications, as indicated on the label near the fuel tank cap. Condition 5: The ABS warning light intermittently illuminates. Cause: Improper adjustment of the brake light switch; poor internal contact in the brake light. Solution: Start the engine, press the brake pedal, and push the brake switch linkage down fully with your fingers. Release the brake pedal to complete the self-setting process. Replace the brake light switch if necessary. If the ABS warning light is on, it is advisable not to continue driving, as it indicates a malfunction in the vehicle's anti-lock braking system. During emergency braking, if the wheels lock up, the vehicle may skid uncontrollably, preventing the driver from slowing down or adjusting the vehicle's trajectory, posing significant safety risks.