Braking System

Air In ABS Module Symptoms

Mike Cross
Updated Oct 17, 2020

Your brakes are a key component in your car. This is because without them you will not be able to stop and if you can’t stop, then you will wreck. That is why it is important to make sure to keep your brakes working.

One system in your car that helps keep your breaks working right is the ABS system. This is the Anti-Locking Brake System. If your brakes lock up while driving, it can lead to sliding and not stopping. That is why you don’t want your brakes to lock.

In this article, we will look at the signs of your ABS system not working and also the signs that your ABS module might be going bad or having errors. Read on to learn all the possible warnings of a failing ABS module.

Air In Abs Module Symptoms
Air In Abs Module Symptoms

How does ABS work?

The ABS module is responsible for judging the wheel speed of your wheels and make sure that your brakes aren’t trying to lock up.

If your brakes lock up and can cause sliding and issues with steering. The way the module makes sure that the brakes don’t lock up is if it notices problems with the wheel speed it controls a valve which adjusts the pressure of the brakes on that wheel. This will make sure you don’t have problems.

If your abs light comes on though, then it means you don’t have anti-locking brakes when it is on.

First before checking the ABS module though you need to make sure that it is the ABS light on and not your other brake light.

Your other brake light may come on if you have bad pads which will also come with grinding sounds. If it is the ABS light though, then it could be caused by a variety of reasons. Read on you learn the possible reasons for a failing ABS module.

Unresponsive Brake Pedal.

The first sign that the ABS module could be going out is an unresponsive brake pedal. This means that you press the brake pedal and nothing seems to happen. This normally doesn’t happen all at once though, which is a good thing because if it did you would wreck. However, with time if you notice you have to press the brake pedal harder to get the car to stop or if you notice it taking longer for your vehicle to stop, then it is a good idea to have your brake system looked at so things don’t go out on you completely.

ABS light is on.

Like it has been said, if the ABS light is on, then you have a problem with your anti-locking brake system. The ABS module is not working right. The ABS light is like a check engine light for your brakes. If the light is on, then it is a good sign that you have issues going on and need to get the system check as soon as possible before you have bigger problems.

Locking Brakes

Locking Brakes
Locking Brakes

The last sign is a sure sign that your ABS module needs to be replaced, and that is locking brakes. If you notice you have to pump the brakes to get the car to stop or notice you start sliding when hitting the brakes, then that is a sign they are locking. A failing ABS module can happen sporadically and like it has been said may not happen all at once. That is why it is a good idea to have things checked as soon as you start noticing problems. Also, if you have grinding or noises that go along with the heavy braking and loss of traction, then this is even more warning that something is wrong. However, check to make sure your brake pads are good first before having the ABS module replaced.

False Alarm

Sometimes though your ABS light will come on and it will be a false alarm. That is because wires can get messed up and if that happens, the light will come on. If you notice the light only on bumpy gravel roads for instance, then it might just be loose or damaged wires. Before replacing the ABS module inspect the cables and make sure they are all connected correctly and that there are no shorts in them. If any wires look damaged, fix them first and see if that solves the problem. If it does great, if not, then at least you know it wasn’t them. Also, a bad fuse can lead to the ABS light coming on. The fuse is easy to check and really should be tested before the wires. If the fuse is blown, then just replace it and that will fix the light coming on.

Another reason why the ABS light might be coming on besides a bad ABS module is that the wheel speed sensors might be going bad or in the wrong position. This is again a common issue if you drive on gravel or bumpy roads a lot. The sensors have to be in the right position to measure wheel speed, and if they aren’t, then the ABS light will come on. You can check each sensor and measure the gap between them in the wheels to make sure that it is the right distance. If it is then great, it is now time to test the sensor to see if it is working right, but if the gap is not the right distance, you can fix it and see if that fixes the problem. If you have a sensor that tests badly, then replace it, and that should fix the ABS light problem assuming that the ABS module doesn’t also have a problem.

Ways to know if ABS Module is bad.

So, what is the best way to know if the ABS module is bad or if it is something else causing the ABS light?

Well, you can use a scan tool and plug it into the OBD2 port. If the ABS module is bad, then your system will have codes indicating that.

If the module is not bad however then your computer will have codes for the sensors or not have codes at all.

If there are no codes, then you can check the other causes of an ABS light, but if it does have codes, you will know to replace the ABS module. And i recommend you to look at best obd2 scanner to have one, it will help you find the code.


After reading this, you now know the signs of a bad or failing ABS module. You know that if your brakes lock sporadically and that the brake pads are okay, then the module is probably failing. You also know that if you keep having to press the brakes harder to be able to stop, that the system is probably also failing. You know the best way through to know if the ABS module is going bad is to check the engine codes if the light is on. If there are codes, then it is a bad ABS module, but if there are no codes, then you know to check the wheel speed sensors, the fuse, or the wires of the ABS module. Now that you know these things though you are well on your way to figuring out if your ABS module is bad the next time your ABS light comes on.

Mike Cross
Life is too short to drive with stock audio

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5 comments on “Air In ABS Module Symptoms”

  1. I have no codes or lights replaced 4 caliperd drained the old fluid added new had shop use computer to bleed and one wont get fluid past the module ??

    1. dear Andrew mathews
      did you solve the problem ?
      if yes please tell me what was that and how you fix it

    2. I just had to replace the hub and barring assembly in my 2000 GMC Sierra 1500 4x4.
      No abs light on, however at slow speed if I turn my wheel and touch my brake pedal the abs goes crazy and I can't stop. Nearly ran over a pedestrian the other day in a parking lot.
      Everything is new, sensor & wire from hub to connector.
      Could there be air trapped or maybe the controller is bad?

  2. This was informative and easy to understand. You have given me a place to start. I think I have been falsely diagnosed at the dealership. So say I end up having a faulty module, what did I do to cause that? I can't find anything anywhere that says what causes the module to go bad. Great article!

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