What does the ABS warning light mean?

[EleanorLynn]

There are various conditions when the ABS light is on, with different causes and solutions for each condition, as detailed below: Condition 1: ABS warning light stays on (most common). Cause 1: The ABS wheel speed sensor's sensing part is covered by mud, sludge, or other contaminants, affecting its ability to detect the corresponding speed signal. This prevents the ABS control unit from determining the vehicle speed or 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 tone ring to restore normal function. Cause 2: Poor signal due to loose system wiring connections or poor contact in the ABS relay, leading to system malfunction. Solution: Inspect wiring connections and reconnect any loose parts. Condition 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple electrical devices are in use, battery voltage drops below 10.5V. As engine speed increases, voltage rises, and the ABS light turns off. This may also occur due to low system supply voltage, such as poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect the charging system; verify power supply (e.g., voltage relay or poor power contact). Condition 3: ABS warning light stays on after engine start but turns off when the engine is turned off (IGFF). Cause: Poor grounding contact in the ABS hydraulic valve body; poor contact in the ABS hydraulic valve body wiring connector; ABS control unit failure. Solution: Loosen and retighten the hydraulic valve body ground screw, cleaning the contact surface if necessary; check for enlarged connector gaps; replace the ABS or ABS/ASR control unit. Condition 4: ABS warning light illuminates during high-speed driving. Cause: The ABS control unit detects a significant discrepancy between rear and front wheel speeds; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's tire and wheel rim specifications, typically found on the label near the fuel filler cap. Condition 5: ABS warning light intermittently illuminates. Cause: Improperly adjusted brake light switch; poor internal contact in the brake light. Solution: With the engine running, press the brake pedal and push the brake switch linkage down fully with your finger, then release the pedal to complete self-positioning; replace the brake light switch if necessary. If the ABS warning light is on, it is recommended not to continue driving. An illuminated ABS light indicates a malfunction in the anti-lock braking system. During emergency braking, locked wheels may cause the vehicle to skid uncontrollably, preventing the driver from slowing down or adjusting the vehicle's path, posing significant safety risks.