What Causes the ABS Light to Illuminate in a Buick Excelle?

[DelLilliana]

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 its ability to detect the corresponding wheel speed signal. This prevents the ABS control unit from determining the vehicle speed or wheel slip rate, thus failing to issue appropriate commands to regulate 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: Poor signal transmission due to loose system wiring connections or faulty ABS relay contacts. Solution: Inspect wiring connections and reconnect any loose terminals. State 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple electrical components are in use, battery voltage drops below 10.5V. As engine speed increases, voltage rises, causing the ABS light to turn off. This may also indicate insufficient power supply voltage to the ABS system due to poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect the charging system; verify power supply (e.g., voltage relay or poor power contact). State 3: ABS warning light remains illuminated after engine start until the engine is turned off (IGFF). Cause: Poor grounding connection of the ABS hydraulic valve body; faulty wiring harness connector at the ABS hydraulic valve body; ABS control unit malfunction. Solution: Loosen and retighten the hydraulic valve body ground screw, 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 specified tire and wheel rim dimensions, typically listed on the fuel filler cap label. State 5: ABS warning light intermittently illuminates. Cause: Improper brake light switch adjustment; internal contact failure in the brake light. Solution: With the engine running, fully depress the brake pedal and manually push the brake switch linkage downward to complete self-positioning; replace the brake light switch if necessary. When the ABS warning light is illuminated, it is recommended to avoid continued driving. An illuminated ABS light indicates a malfunction in the anti-lock braking system. During emergency braking, wheel lock-up may occur, causing loss of vehicle control and skidding, which prevents the driver from decelerating or adjusting the vehicle's trajectory, posing significant safety risks.