What causes the ABS light to illuminate in a Sylphy and how to troubleshoot it?

[DelNadia]

ABS light illumination can occur in various states, with different causes and solutions for each state. Details are as follows: 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 speed signal. This prevents the ABS control unit from determining the vehicle speed and calculating wheel slip rates, thus failing to issue appropriate commands for brake adjustment. Solution: Clean contaminants 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 system wiring connections or faulty ABS relay contacts. Solution: Inspect wiring connections and reconnect any loose terminals. State 2: ABS warning light illuminates intermittently, turning off during acceleration. Cause: When multiple electrical components are in use, battery voltage drops below 10.5V. The light extinguishes when engine speed increases and voltage rises. 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 charging system; examine power supply components (such as voltage relays or poor power connections). State 3: ABS warning light remains illuminated after engine start until engine IGFF position. Cause: Poor grounding connection of ABS hydraulic valve body; faulty wiring harness connector of ABS hydraulic valve body; ABS control unit 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 control unit. State 4: ABS warning light illuminates during high-speed driving. Cause: ABS control unit detects excessive speed difference between rear and front wheels; incorrect tire specifications or incorrect wheel rim specifications. Solution: Verify proper tire and wheel rim specifications according to vehicle requirements, referencing the label near the fuel filler cap. State 5: ABS warning light illuminates intermittently. Cause: Improper brake light switch adjustment; internal contact failure in brake lights. Solution: With engine running, depress brake pedal and manually push the brake switch linkage downward completely, then release pedal to complete self-positioning; replace brake light switch if necessary. When the ABS warning light is illuminated, it's recommended to avoid continued driving. An illuminated ABS light indicates 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 vehicle trajectory, posing significant safety risks.