What Causes the ABS Yellow Light on the Dashboard to Stay On?
2 Answers
There are various states of the ABS light being on, with different causes and solutions for each state. The details are as follows: State 1: ABS warning light stays on continuously (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 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: Poor signal quality due to loose connections between system lines or poor contact of the ABS relay, leading to system failure. Solution: Check the line connections and reconnect any loose parts. State 2: ABS warning light intermittently turns on but goes off when accelerating. Cause: When multiple vehicle electrical devices are in use, the battery voltage drops below 10.5V. As the engine speed increases, the voltage rises, and the ABS indicator light turns off. The ABS system's power supply voltage is too low, possibly due to poor terminal contact or grounding issues. Solution: Check the battery's specific gravity, inspect the charging system, and verify the power supply (e.g., voltage relay or poor power contact). State 3: ABS warning light stays on after engine startup and only turns off when the engine is turned off (IGFF). Cause: Poor grounding contact of the ABS hydraulic valve body; poor contact in the ABS hydraulic valve body's wiring connector; ABS computer malfunction. Solution: Loosen the grounding screw of the hydraulic valve body, then retighten it. Clean 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 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 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, and 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. If the ABS warning light is on, it is recommended not to continue driving. An illuminated ABS light indicates a malfunction in the vehicle's anti-lock braking system. During emergency braking, if the wheels lock up, the vehicle may skid uncontrollably, making it difficult for the driver to slow down or adjust the vehicle's trajectory, posing significant safety risks.
I've been driving for over a decade. When the ABS warning light comes on, I usually first check if the wheel speed sensors are covered by mud or snow, as dirt can block the signal and trigger the light. It could also be a blown fuse—open the engine compartment's fuse box and look for the relevant fuse to replace. An ABS system failure means the wheels might lock up during braking, which is especially dangerous on slippery roads, so I slow down and maintain distance when driving. Aging wiring or loose connections are also common causes, requiring a professional to read the fault codes with a diagnostic tool. Don't ignore it—ABS can be life-saving in emergencies, so I recommend getting it checked at a repair shop as soon as possible. When washing the car, pay attention to cleaning the sensor area to prevent issues. If the light comes on while driving on the highway, be extra cautious and avoid sudden braking.
