What are the causes of ABS ESC failure?

[Maxine]

ABS warning light can indicate various conditions, each with different causes and solutions as follows: Condition 1: ABS warning light stays on (most common). Cause 1: The ABS wheel speed sensor's sensing area is covered by mud, dirt, or other contaminants, affecting its ability to detect wheel speed signals. This prevents the ABS control unit from determining vehicle speed or wheel slip rate, thus failing to issue appropriate commands to regulate braking. Solution: Clean contaminants from the wheel speed sensor and adjust the gap between the sensor and tone ring to restore normal function. Cause 2: Loose wiring connections or poor ABS relay contact causing signal interference. Solution: Inspect wiring connections and re-secure any loose parts. Condition 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: Battery voltage drops below 10.5V when multiple electrical components are in use. The light extinguishes when engine speed increases voltage. Possible low system voltage due to poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect charging system; examine power supply (e.g., voltage relay or loose power connections). Condition 3: ABS light remains on after engine start until ignition OFF. Cause: Poor ground connection at ABS hydraulic valve body; faulty wiring harness connection; ABS control module malfunction. Solution: Loosen and retighten valve body ground screw (clean contact surface if necessary); check connector gaps; replace ABS or ABS/ASR control module. Condition 4: ABS light activates during high-speed driving. Cause: Significant discrepancy between front/rear wheel speed signals detected by ABS module; incorrect tire or wheel specifications. Solution: Verify correct tire/wheel specifications per vehicle placard (typically on fuel filler door). Condition 5: Intermittent ABS warning light activation. Cause: Improper brake light switch adjustment; internal switch contact failure. Solution: With engine running, fully depress brake pedal while manually pushing switch lever downward, then release pedal to reset position; replace brake light switch if needed. When the ABS warning light is illuminated, continued driving is not recommended as it indicates anti-lock braking system malfunction. During emergency braking, wheel lock-up could cause loss of vehicle control, preventing speed reduction or trajectory adjustment, posing significant safety risks.