What Causes the ABS Light and Steering Wheel Light to Illuminate?

[ONoah]

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 lit (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 module from determining the vehicle speed and wheel slip rate, thus 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: Poor signal transmission due to loose system wiring connections or faulty ABS relay contacts, leading to 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 drops below 10.5V. As engine speed increases, voltage rises, causing the ABS indicator to turn off. This may also occur if the ABS system's power supply voltage is too low due to poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect the charging system; examine the power supply (e.g., voltage relay or poor power contact). State 3: ABS warning light remains lit after engine start until the engine is turned off (IGFF). Cause: Poor grounding connection of the ABS hydraulic valve body; faulty wiring connections at the ABS hydraulic valve body; ABS control module malfunction. Solution: Loosen and retighten the hydraulic valve body's grounding screw, cleaning the contact surface if necessary; check for enlarged terminal gaps; replace the ABS or ABS/ASR control module. State 4: ABS warning light illuminates during high-speed driving. Cause: The ABS control module detects a significant discrepancy between rear and front wheel speed signals during high-speed driving; incorrect tire or wheel rim specifications. Solution: Refer to the vehicle's specified tire and wheel rim dimensions, typically listed on the fuel cap label. State 5: ABS warning light illuminates intermittently. Cause: Improper adjustment of the brake light switch; internal contact issues within the brake light. Solution: With the engine running, press the brake pedal fully, manually push the brake switch linkage downward to its limit, then release the pedal to complete self-adjustment; replace the brake light switch if necessary. If the ABS warning light is illuminated, it is advisable to avoid continued driving. An illuminated ABS light indicates a malfunction in the anti-lock braking system, which may cause wheel lock-up during emergency braking, leading to loss of vehicle control, skidding, and inability to decelerate or adjust trajectory, posing significant safety risks.

[LaColin]

I remember the ABS light and steering wheel light came on simultaneously, which happened to me twice—once in rainy weather and another time during winter after rain. The ABS light indicates an anti-lock braking system alert, while the steering wheel light usually signals an issue with the power steering system. Why do they appear together? It’s likely due to a dirty or faulty wheel speed sensor, as these sensors inside the wheel hub tend to accumulate dust, causing signal interference that affects both systems. When the sensor sends incorrect feedback, the vehicle’s computer may misinterpret it as steering instability or braking failure. My suggestion is to first stop the car, turn off the engine, and restart to see if the lights disappear. If they remain on, check the tire pressure and inspect the wheel speed sensor for looseness—try gently wiping it with a cloth. Don’t ignore this issue, as it can compromise emergency braking effectiveness and steering responsiveness, especially on slippery roads. Last time I overlooked it, I nearly had an accident, and later spent a few hundred bucks at a professional shop to replace the sensor. Regularly cleaning the sensor area during maintenance can significantly reduce the chances of such failures.