There are multiple states of the ABS light illumination, with different causes and solutions for each state, as detailed below: State 1: ABS warning light remains constantly on (most common). Cause 1: The ABS wheel speed sensor's sensing area 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 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 signal ring to restore normal function. Cause 2: Poor signal transmission due to loose connections between system wiring 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 vehicle electrical devices are in use, the battery voltage drops below 10.5V. As engine speed increases, voltage rises, causing the ABS light to turn off. This may also occur if the ABS system power supply voltage is too low due to poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect the charging system; examine power supply components (e.g., voltage relay or poor power contact). State 3: ABS warning light remains on after engine start until engine IGFF (ignition off). Cause: Poor grounding connection of ABS hydraulic valve body; faulty wiring connector of ABS hydraulic valve body; ABS control unit malfunction. Solution: Loosen and retighten the hydraulic valve body grounding screw, cleaning contact surfaces if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR control unit. State 4: ABS warning light illuminates during high-speed driving. Cause: During high-speed driving, the ABS control unit detects excessive difference between rear and front wheel speed signals; incorrect tire or wheel rim specifications. Solution: Refer to vehicle's tire and wheel rim specifications, typically found on the label near the fuel tank cap. State 5: ABS warning light intermittently illuminates. Cause: Improper adjustment of brake light switch; poor internal contact of brake lights. Solution: With engine running, depress brake pedal, manually push brake switch linkage downward to its limit, then release pedal to complete self-positioning; replace brake light switch if needed. When the ABS warning light is illuminated, it is advised not to continue driving as this indicates a malfunction in the anti-lock braking system. During emergency braking, if wheels lock up, the vehicle may skid uncontrollably, preventing the driver from decelerating or adjusting the vehicle's trajectory, posing significant safety risks.
