What does the ABS warning light in a car mean?

[LeCody]

ABS light can illuminate in various states, with different causes and solutions for each state. The details are as follows: State 1: ABS warning light stays 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 vehicle's speed signal. This prevents the ABS control unit from determining the speed and calculating the 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 faulty ABS relay contacts. Solution: Inspect wiring connections and reconnect any loose parts. State 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple electrical devices are used, the battery voltage drops below 10.5V. As engine speed increases and voltage rises, the ABS light turns off. This may also occur due to insufficient power supply voltage to the ABS system, such as poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect the charging system; examine the power supply (e.g., voltage relay or poor power contact). State 3: ABS warning light stays on after engine start and only turns off when the engine is turned off (IGFF). Cause: Poor grounding connection of the ABS hydraulic valve body; loose wiring connector of the ABS hydraulic valve body; ABS control unit malfunction. Solution: Loosen and retighten the grounding screw of the hydraulic valve body, cleaning the contact surface if necessary; check for enlarged connector gaps; replace the ABS or ABS/ASR control unit. State 4: ABS warning light illuminates during high-speed driving. Cause: The ABS control unit detects a significant discrepancy between rear and front wheel speed signals during high-speed driving; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's tire and wheel rim specifications, typically listed on the fuel tank cap label. State 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 push the brake switch linkage fully downward with a 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 not recommended 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 trajectory, posing significant safety risks.