ABS light can indicate various conditions, each with different causes and solutions, as detailed below: Condition 1: ABS warning light stays 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 correct wheel speed signal. This prevents the ABS computer from determining the vehicle speed and wheel slip rate, thus failing to issue appropriate commands to adjust 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 due to loose connections in the system wiring or poor contact in the ABS relay, leading to system malfunction. Solution: Check all 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, the battery voltage may drop below 10.5V. As the engine speed increases and voltage rises, the ABS light turns off. This can also occur if the ABS system's power supply voltage is too low due to poor contact or grounding issues. Solution: Check the battery's specific gravity, inspect the charging system, and verify the power supply (e.g., voltage relay or poor power contact). Condition 3: ABS warning light stays on 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, or a faulty ABS computer. Solution: Loosen and retighten the grounding screws on the hydraulic valve body, clean contact surfaces if necessary, check for enlarged connector gaps, and replace the ABS or ABS/ASR computer if needed. Condition 4: ABS warning light illuminates during high-speed driving. Cause: The ABS computer detects a significant discrepancy between rear and front wheel speed signals during high-speed driving, possibly due to incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's specified tire and wheel rim sizes, typically listed on the fuel tank cap sticker. Condition 5: ABS warning light intermittently illuminates. Cause: Improper adjustment of the brake light switch or poor internal contact in the brake light. Solution: With the engine running, press the brake pedal and manually push the brake switch linkage down fully, then release the pedal to reset its position. Replace the brake light switch if necessary. If the ABS warning light is on, it is advised not to continue driving, as this indicates a malfunction in the anti-lock braking system. During emergency braking, locked wheels can cause loss of control and skidding, preventing the driver from slowing down or adjusting the vehicle's path, posing significant safety risks.
