What causes the ABS light to illuminate in a Dongfeng Peugeot?

[Lester]

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 speed signal. This prevents the ABS control unit from determining the vehicle speed and wheel slip rate, thereby 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: Loose connections in the system wiring or poor contact in the ABS relay can lead to signal issues and system malfunction. Solution: Inspect wiring connections and reconnect any loose parts. State 2: ABS warning light illuminates intermittently but turns off during acceleration. Cause: When multiple 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 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 illuminated 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 the contact surface if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR computer if needed. 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 the vehicle's specified tire and wheel rim dimensions, typically found on the label near the fuel filler cap. State 5: ABS warning light illuminates intermittently. Cause: Improper adjustment of brake light switch; poor internal contact in brake lights. Solution: With engine running, depress brake pedal, manually push the brake switch linkage fully downward, then release the pedal to complete self-setting; replace brake light switch if necessary. When the ABS warning light is illuminated, it is recommended not to continue driving as it indicates a malfunction in the vehicle's anti-lock braking system. During emergency braking, if wheels lock up, the vehicle may skid uncontrollably, preventing the driver from decelerating or adjusting the vehicle's trajectory, posing significant safety risks.