ABS light illumination can occur in various states, 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 dirt, mud, or other contaminants, affecting the sensor's ability to detect the corresponding wheel speed signal. This prevents the ABS control module from determining the vehicle speed and calculating the wheel slip ratio, 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: Loose connections in the system wiring or poor contact in the ABS relay cause signal issues leading to system failure. 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 components 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 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 power supply components (e.g., voltage relay or poor power contact). State 3: ABS warning light remains on after engine start until engine IGFF turns it off. Cause: Poor grounding contact in the ABS hydraulic valve body; poor electrical connector contact in the ABS hydraulic valve body; ABS computer malfunction. Solution: Loosen and retighten the hydraulic valve body ground screw, cleaning contact surfaces if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR computer. State 4: ABS warning light illuminates during high-speed driving. Cause: During high-speed driving, the ABS computer 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 filler cap. State 5: ABS warning light intermittently illuminates. Cause: Improper brake light switch adjustment; poor internal contact in brake lights. Solution: With engine running, depress brake pedal, manually push brake switch linkage downward to its limit, then release brake pedal to complete self-positioning; replace brake light switch if needed. When the ABS warning light is on, it's recommended to avoid continued driving as it indicates a malfunction in the anti-lock braking system. During emergency braking, locked wheels may cause loss of vehicle control and skidding, preventing the driver from decelerating or adjusting the vehicle's path, posing significant safety risks.
