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Why is your ABS light on?

Why is your ABS light on?

Most people don't know what their car's Anti-Lock Brake System (ABS) is until they see the warning light in their instrument cluster. The ABS system is designed to monitor wheel speed and modulate brake fluid pressure to actively prevent the wheels from locking up.

Reasons your ABS light is on.

If the ABS light is on the system is not functioning correctly, the vehicle should be seen by a trusted mechanic. A mechanic can use a scan tool to see what diagnostic trouble codes the vehicle is presenting, and begin to troubleshoot the problem. Some common reasons your ABS light would come on are:

  • a blown fuse for the system
  • broken or dirty wheel speed sensors
  • low brake fluid
  • ABS control module not working

Blown Fuses

All electrical systems in your vehicle will have a designated fuse in the fuse box(es). Fuses have a thin wire through which electrical current passes. If too much electricity passes through, the fuse wire will burn through and the fuse will blow, preventing that current from burning through wires, damaging electrical components, or even causing a fire. Because fuses are a simple fix, it is worth checking for blown fuses when your ABS light comes on. The fuse box diagram and corresponding fuse can be found in your owner's manual. Please note, when fuses blow there is a reason. If your ABS fuse blows, there might be a serious problem with your ABS module. Never replace a fuse with one that is rated for higher current, as this may lead to more damage to electronics and potentially a fire.

Malfunctioning Wheel Speed Sensors

Wheel Speed Sensors send data on your wheel speed to your vehicle's ABS. Because these sensors are located close to the wheels they can be damaged by the heat from the brakes, dirt from the road, and debris. If your ABS light comes on, and you find a speed sensor code stored, check the sensors and clean or replace them as needed. Wheel speed sensors are a necessary part of safely operating your vehicle, so you should ensure these are functioning correctly before driving.

Low Brake Fluid

The ABS system relies on hydraulic brake fluid to work. If your brake fluid reservoir is low, there is a leak in the system, or air in the lines your ABS systems may not be applying balanced pressure to the brakes. Low brake fluid can cause dangerous situations when trying to brake, and should be corrected immediately.

ABS Control Module Not Working

The ABS Control Module, and occasionally the associated pump & motor, can stop working over time. This can happen because of corroded wires, or because of damage or wear within the module itself. All wires in the ABS system should be free from corrosion, and the connections tight. If the vehicle codes are cleared after checking the wiring and the problem returns you may have a malfunctioning ABS module. This module can be expensive to replace, and a new module might need reprogramming. Depending on the codes that the module is presenting, a rebuild service may be able to repair your module for much less, and will not need reprogramming.

If your ABS light is on or the system is not functioning properly we may be able to help. Shop our ABS Module Rebuilds. If you can't find what you're looking for contact us to tell us the year, make, and model of your vehicle and what codes it is presenting and we'll let you know if we can rebuild your module.


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