Why is the ABS brake light on?

In vehicles equipped with an Anti-lock Braking System (ABS), a ring is embedded in each wheel, and a sensor above it sends information about the wheel’s rotational speed to the central computer or ECU. If the ECU detects that one or more wheels are rotating slower than the others during braking, it reduces brake pressure to allow that wheel to rotate more freely and prevent locking. However, like any system, ABS can encounter issues.

What is the ABS brake light?
To alert the driver of ABS-related problems, car manufacturers have designed a warning light, usually yellow or orange, labeled “ABS” on the dashboard. This light illuminates when there’s an issue with the ABS.

Why Does the ABS Brake Light Turn On?
Several factors can cause the ABS brake light to illuminate:

ABS Control Module Failure: The ABS control module is a crucial component that monitors wheel speed through sensors and sends instructions to the ECU. Any malfunction in this module will trigger the warning light.
Low Brake Fluid: Modern braking systems are hydraulic, relying on brake fluid to transmit force to the brakes. If the brake fluid level drops due to leaks or quality deterioration, the system’s efficiency is compromised, and the ABS light will turn on.
Wheel Speed Sensor Malfunction: As the name suggests, wheel speed sensors monitor wheel rotation. If these sensors malfunction, the ABS will be unable to function correctly, and the warning light will illuminate.
Relays and Fuse Failures: Any malfunction within the ABS, such as a faulty relay or blown fuse, can activate the warning light.
Resolving the ABS Brake Light Issue
If you encounter any of these symptoms, it’s advisable to consult a qualified mechanic. Many ECU errors can be diagnosed using a diagnostic scanner, allowing the mechanic to identify the specific issue with the ABS and provide necessary repairs.