* Low Brake Fluid: This is the easiest and cheapest thing to check first. Low brake fluid can trigger the ABS light because the ABS system shares the same fluid reservoir. Check your brake fluid level in the master cylinder reservoir.
* Faulty Wheel Speed Sensor: These sensors monitor the speed of each wheel. If one or more sensors are malfunctioning (dirty, damaged, or wired incorrectly), the ABS control module will detect this and illuminate the light. This is a common cause. They are located near the wheel hubs.
* ABS Control Module Failure: The ABS control module is the "brain" of the system. If it fails, it will illuminate the light. This is a more expensive repair, often requiring replacement of the module.
* Wiring Issues: Damaged, corroded, or loose wiring within the ABS system can cause intermittent or constant illumination of the light. This can be difficult to diagnose.
* Faulty ABS Pump/Motor: The hydraulic pump within the ABS module can fail, leading to the light staying on.
* Faulty Tone Ring (ABS Ring): The tone ring is a part of the wheel hub that the wheel speed sensor reads. If it's damaged or corroded, the sensor won't read correctly.
* Fuse Problem: Though less common, a blown fuse related to the ABS system could be the culprit. Check your fuse box for the correct fuse.
How to Diagnose:
You'll likely need a scan tool capable of reading ABS codes to pinpoint the exact problem. Auto parts stores often offer free code reading services. The code will help narrow down the possible causes. Simply checking the brake fluid level is a good first step. If the fluid is low, you need to find and repair the brake leak *before* focusing on the ABS system.
Important Note: While the car will still brake, the ABS functionality will be disabled if the light is on. This means you'll lose the anti-lock braking capability in emergency situations, potentially leading to a loss of control. It's crucial to get this issue diagnosed and repaired as soon as possible.
