What does it mean when the ABS light on the car dashboard is on?
2 Answers
When the car displays an ABS warning, it means there is a fault in the vehicle's Anti-lock Braking System. During emergency braking, if the wheels lock up, the vehicle may lose control and skid, making it difficult for the driver to slow down or adjust the vehicle's trajectory, which poses a significant safety hazard. There are several states in which the ABS light may illuminate, each with different causes and solutions, as detailed below: State 1: ABS warning light stays on constantly (most common). Cause 1: The ABS 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's speed or the wheel's slip rate, thus failing to issue appropriate commands to regulate braking. Solution: Clean the dirt from the speed sensor and adjust the gap between the speed sensor and the signal 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 failure. Solution: Inspect the wiring connections and reconnect any loose parts. State 2: ABS warning light intermittently illuminates but turns off when accelerating. Cause: When multiple vehicle electrical devices are in use, the battery voltage may drop below 10.5V. As the engine speed increases and voltage rises, the ABS warning light turns off. This can also occur if the ABS system's 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 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 control unit. Solution: Loosen and retighten the grounding screw on the hydraulic valve body, cleaning the contact surface if necessary; check if the connector gap has widened; replace the ABS or ABS/ASR control unit. State 4: ABS warning light illuminates during high-speed driving. Cause: At high speeds, the ABS control unit detects a significant discrepancy between the rear and front wheel speed signals; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's tire and wheel rim specifications, as indicated on the label near the fuel tank cap. 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, push the brake switch linkage down fully with your fingers, then release the brake pedal to complete the self-setting position; replace the brake light switch if necessary.
As an ordinary person who commutes by car frequently, when I see the ABS light on the dashboard, my first reaction is that there's an issue with the anti-lock braking system. Once the ABS light comes on, it means the system has detected a fault during self-check and requires prompt attention. Common causes include wheel speed sensors being blocked by mud or dust, aging or short-circuited wiring, ABS pump failure, or a blown fuse. Sensors can easily trigger false alarms due to contamination from wet or rainy road conditions; wiring issues are often caused by aging or loose connectors. If you're a new driver, don't worry too much—you can try turning off the engine and restarting to see if the light disappears. If it remains on, it's best to visit a repair shop as soon as possible for a computer diagnosis to pinpoint the exact cause. Since ABS prevents wheel lock-up during emergency braking and ensures steering control, especially at high speeds or in snowy conditions, driving without ABS significantly increases the risk of accidents. I always remind my friends to clean the sensors regularly and check them monthly.
