What does it mean when the ABS light on the dashboard is on?
3 Answers
When the ABS light is displayed on the car, it means there is a malfunction 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 various states of the ABS light being on, and the causes and solutions differ depending on the state. The details are as follows: State 1: ABS warning light stays on (most common). Cause 1: The ABS speed sensor's sensing part is covered by dirt, mud, or other contaminants, affecting the sensor's ability to detect the corresponding speed signal. This prevents the ABS computer from determining the vehicle's speed and the wheel's slip rate, thus failing to issue appropriate commands to adjust 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 between system wires or poor contact in the ABS relay can lead to signal issues and system failure. Solution: Check the wire connections and reconnect any loose parts. State 2: ABS warning light intermittently turns on but goes off when accelerating. Cause: When multiple electrical devices are used, the battery voltage drops below 10.5V. As the engine speed increases, the voltage rises, and the ABS light turns off. This may 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; 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; ABS computer malfunction. Solution: Loosen and retighten the grounding screws of the hydraulic valve body, cleaning the contact surface if necessary; check if the connector gap has widened; replace the ABS or ABS/ASR computer. State 4: ABS warning light turns on during high-speed driving. Cause: During high-speed driving, the ABS computer detects a significant difference 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 fuel tank cap sticker. State 5: ABS warning light intermittently turns on. Cause: Improper adjustment of the brake light switch; poor internal contact in the brake light. Solution: Start the engine, press the brake pedal, push the brake switch linkage down with your finger, then release the brake pedal to complete self-setting; replace the brake light switch if necessary.
I've been driving for twenty years, and when the ABS light on the dashboard comes on, you should take it seriously. It indicates a problem with the vehicle's anti-lock braking system. I've encountered this situation several times—sometimes it's because the sensor on one of the tires is covered in mud, which is especially common during rain or snow; other times, key components of the braking system need inspection. When driving with this issue, the effect is quite noticeable, especially during sudden braking when the steering wheel shakes significantly. Although the brakes still function, without the anti-lock feature, the car is prone to skidding when turning in the rain. In such cases, it's best not to drive too fast, particularly on rainy days. For safety's sake, get it checked at a repair shop as soon as possible—this system is crucial for driving safety.
Having worked in an auto repair shop for over a decade, I often encounter customers asking about the ABS warning light coming on. Simply put, it means the anti-lock braking system has detected an abnormal condition. Possible causes include loose wiring of the wheel speed sensor or debris covering the sensor; it could also be an ABS module connector contact issue, which is particularly common on gravel roads; of course, the most troublesome scenario is a failure in the control module itself. The last time my own old car had this light on, we found that the left front wheel sensor wire had been chewed through by a rat. While the car remains drivable in such cases, the risk of wheel lock-up during emergency braking and loss of steering control increases significantly. I recommend getting a system diagnosis as soon as possible when the light appears.
