When the ABS warning light is on, it is recommended not to continue driving because the illuminated ABS light indicates a malfunction in the vehicle's 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 slow down or adjust the vehicle's trajectory, posing significant safety risks. The ABS warning light can illuminate under various conditions, each with different causes and solutions, as detailed below: Condition 1: ABS warning light stays on continuously (most common). Cause 1: The ABS 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's speed or the wheel's slip rate, thus failing to issue appropriate commands to regulate braking. Solution: Clean the dirt from the speed sensor and adjust the gap between the sensor and the signal ring to restore normal function. Cause 2: Loose connections between system wires or poor contact in the ABS relay can lead to signal issues and system failure. Solution: Inspect wire connections and reconnect any loose parts. Condition 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple vehicle electrical devices are in use, the battery voltage may drop below 10.5V. As the engine speed increases, the voltage rises, causing the ABS warning light to turn off. This may also occur if the ABS system's power supply voltage is too low due to poor wire 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: ABS warning light stays 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, faulty wiring connections in the ABS hydraulic valve body, or ABS computer malfunction. Solution: Loosen and then retighten the grounding screw on the hydraulic valve body, cleaning the contact surface if necessary. Check for enlarged gaps in the connectors and replace the ABS or ABS/ASR computer if needed. Condition 4: 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. This may also occur if the tire or wheel rim specifications are incorrect. Solution: Refer to the vehicle's tire and wheel rim specifications, as indicated on the fuel tank cap label. Condition 5: ABS warning light intermittently illuminates. Cause: Improper adjustment of the brake light switch or poor internal contact in the brake light. Solution: Start the engine, press the brake pedal, and use a finger to push the brake switch linkage all the way down. Then, release the brake pedal to complete the self-setting process. Replace the brake light switch if necessary.
