What Causes an ABS Light to Come On? (5 Common Causes)

Updated

ABS is an abbreviation for the Anti-lock Braking System. The ABS is one of the systems in your car that is responsible for keeping you safe and in control of your vehicle in case of emergency due to heavy braking.

The first symptom of a problem with the ABS system is that the ABS light will come on in the instrument cluster in your dashboard. For more information about how an ABS system works and the common causes of an ABS light coming on, please continue reading.

How an ABS System Works

The main role of the anti-lock braking system is to keep you safe from the any accidents and to make sure that you do not lose control of your car (like skidding) in case of any emergency braking.

The ABS is a safety system which has the ability to recognize a stop in the rotation of the wheels during braking while the car is still in motion, and release the brake fluid pressure which allows the wheels to start rotating again.

The system is capable of this because it is fully automated.  This operation may sound simple at first but its importance lies in the controlled stoppage or slowdown of the vehicle while greatly reducing the chances of losing control of the car.

This will allow the car wheels to avoid getting locked up and skidding uncontrollably. But a vehicle’s ABS is also prone to wear and tear and can fail. If you see the ABS light come on, the best course of action is to resolve the issue as soon as possible.

Common Causes When an ABS Light Comes On

#1 – Faulty Wheel Speed Sensor

bad wheel speed sensor

One of the various reasons for the ABS light to illuminate and stay on is a faulty wheel speed sensor. Wheel speed sensors are located inside the center of the wheel and in some cases, inside the transmission.

The Anti-lock Braking System depends on the data from the wheel speed sensor. The wheel speed sensors decide the rate at which the wheels of your vehicle are moving. They transmit that data to the ABS which, upon receiving it from one or more wheels, determines that one or more wheels are moving slower as compared to the others and it releases the pressure of the brake fluid.

This allows the wheels to resume their movement. If there is problem with the wheel speed sensor, whether is covered is grime from regular driving or damaged in some way, the ABS will not get any data from it to control the movement of the wheels.

The wheel speed sensor is mounted really close to the braking system which makes it vulnerable to damage due to high heat caused by the brakes. This damage to wheel speed sensor could cause the ABS light to come on.

#2 – Unresponsive Hydraulic Pump or Valve

bad ABS pump

The ABS releases a hydraulic valve to increase the brake fluid pressure to hinder the wheels from losing friction with the ground when it receives the data from the wheel speed sensors.

This valve or pump is more susceptible to damage probably due to internal wear and tear. One of the causes of this internal wear could be the dirt brake fluid. This could make ABS light to come on.

#3 – Blown Fuse

blown fuse

Like most any system or electrical component, the anti-lock braking system will have its own fuse. Before attempting to replace expensive parts or spend time troubleshooting, make sure the fuse for the ABS is not blown or burnt. A quick check in the fuse box can save you a big headache.

#4 – Faulty ABS Module

bad ABS module

Another reason for the ABS light to come on is ABS module itself being faulty. This could happen due to the corrosion on the wires which could increase their resistance causing delays or no communication between the wheel speed sensor and the ABS.

Even a small amount of corrosion is enough to keep the system from working. The worst case scenario includes the replacement of the computer in the module.

#5 – Low Brake Fluid

brake fluid change

Like most of the braking system, the ABS too relies on hydraulic brake fluid in order to control the pressure. A low level of fluid in the reservoir could prevent ABS from doing its job which can make the ABS light stay on. Too much air in the system is another probable cause of it.

 

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