What Causes the ABS Light to Illuminate in a Great Wall Pickup Truck?

[LukeLee]

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 illuminated (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 speed signal. This prevents the ABS control unit from determining the vehicle speed and calculating the wheel slip rate, thus failing to issue appropriate commands to adjust braking. Solution: Clean the contaminants from the wheel speed sensor and adjust the gap between the sensor and the tone ring to restore normal function. Cause 2: Loose connections between system wiring or poor contact in the ABS relay can 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 vehicle electrical components are in use, the battery voltage may drop below 10.5V. As engine speed increases, voltage rises, causing the ABS light to turn off. This can also occur if the ABS system power supply voltage is too low due to poor terminal contact or grounding issues. Solution: Check the battery's specific gravity; inspect the charging system; examine the power supply (e.g., voltage relay or poor power contact). State 3: ABS warning light remains illuminated after engine start and only turns off when the engine is turned off (IGFF). Cause: Poor grounding contact in the ABS hydraulic valve body; loose wiring connections in the ABS hydraulic valve body; ABS control unit malfunction. Solution: Loosen and retighten the hydraulic valve body's grounding screw, cleaning the contact surface if necessary; check for enlarged terminal gaps; replace the 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 a significant discrepancy between rear and front wheel speed signals; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's specified tire and wheel rim sizes, as indicated 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 manually push the brake switch linkage downward to its limit, then release the pedal to complete self-positioning; replace the brake light switch if necessary. When the ABS warning light is illuminated, it is advisable to avoid continued driving. An 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 skid uncontrollably, preventing the driver from slowing down or adjusting the vehicle's trajectory, posing significant safety risks.