ABS Lights- All You Need To Know

Are you perturbed by your vehicle’s ABS light coming on? Have you been scampering through web pages trying to find answers? Well, now that you have landed here, let us dig deep into the explicit details of ABS and uncover all the answers to your troubling questions.

What is ABS?

Before we get into the boring definition of ABS, let me start off by telling you a true story about my experience in my sans ABS car. I was driving in wet conditions when a dog suddenly sprung off the bushes from the left and made a dash to the other side of the road.  I immediately stepped on the brake pedal, and that sent my car spiraling out of control into the bushes. I was lucky to escape without any serious injuries.

Truth be told, the entire fiasco could have been avoided if my car was fitted with ABS. I hope my experience has made you appreciate the importance of ABS. Now let us quickly get over with the definition.

The Anti-lock Braking System (ABS) is a safety system in your motor vehicle which prevents the wheels from locking up. In other words, the ABS doesn’t allow your car to skid under extreme braking pressure.

What are the major components of ABS?

If you are like me and not willing to meddle with the repairs, I will suggest you skip this section entirely. On the flipside, if you are willing to get your hands dirty, the following list should prepare you for it.

Controller – If the ABS is analogous to a computer, then you can think of the controller as the CPU.

Upon activation, the controller receives information from the other components, processes it and goes on to instruct the other parts about what it should do.

Speed sensors

As its name suggests, the speed sensors monitor the rotational speed of the wheels. These sensors are typically placed inside the hub of each wheel. Although, sometimes they might also be located inside the transmission module.


The valves present in your vehicle regulate the air pressure applied to the brakes. The valve typically has three functions:

  • When the valve is open, the pressure from the master cylinder is exerted on the brake.
  • The valve can shut down the brake line, and this prevents excess pressure from being applied to the brakes.
  • Finally, the valve also exhausts pressure from the brake chamber. In other words, it releases pressure from the brake.

During normal braking, the valve remains in the open state. Under ABS operation, the controller modulates the functioning of the valve as needed.

Hydraulic Pump

When the ABS module is activated, the hydraulic pump and the valves work in conjunction to provide optimum braking performance. When the valve releases pressure from the brake, the controller instructs the pump to increase the pressure.

If you would like to read about the various components of ABS in great details, I would suggest you read this manual – http://www.meritorwabco.com/MeritorWABCO_document/tp9738.pdf. Although it is a handbook on tractor ABS, the fundamentals are the same as your vehicle’s system.

ABS Vs. Conventional Braking System

Interestingly, the conventional braking system outperforms the ABS in a dry, grippy road. This is because, under emergency braking, the conventional braking system maintains a constant pressure on the wheels. Don’t let that fool you though; the ABS outshines the traditional system in slippery conditions.

Under wet conditions, the ABS prevents your vehicle from skidding uncontrollably. It enhances your control under extreme braking by modulating the pressure on the brakes.

What is the significance of the ABS light?

You must have noticed the ABS light coming on when you turn on the ignition. If you are not familiar with the ABS light, it is the indicator in your vehicle’s instrument panel named ABS.

Since you car’s ABS uses various sensors to function properly, it is important to supervise this system. This task is handled by your vehicle’s onboard computer.

The onboard computer periodically checks whether the sensors are properly functioning or not. In case the computer notices any anomalous signals, or it doesn’t receive any form of communication from the sensors, it will flip on the ABS light. If the ABS light stays on while you are driving, it indicates that there is a fault in the system.

What should you do after your ABS light stays switched on?

If you notice the ABS light gets turned on while you are driving, you should immediately stop your vehicle and turn it off. After a while, turn on the ignition and notice your instrument panel once all the warning lights have stabilized. This process will make your car’s onboard computer recheck for any anomalies.

In the occasional case of a glitch, this does the trick, and your ABS light will get switched off. However, if the ABS light is still on, then that indicates a failure in your vehicle’s ABS, and you need to get in touch with your car’s authorized dealer as soon as possible.

Is it safe to drive with your vehicle’s ABS light on?

Let me first get rid of a common misconception that the ABS of your car is always functioning when you step on the brake pedal. The ABS only comes into play under emergency braking situations. Therefore under normal braking, it is the same as a non-ABS vehicle.

So unless there aren’t any other warning lights flashing on the instrument panel, it is fine to drive as long as you stay extra cautious. However, I will suggest you test the brakes a few times before you continue driving. You should be wary of slippery conditions as well. It’s best to avoid driving your vehicle under such circumstances.

If you experience any loss in braking potential while driving, you should immediately stop your car and get in touch with your mechanic or call up your authorized dealer’s helpline.

It is also important to remember that your vehicle’s ABS isn’t a standalone system. Other systems like Traction Control, Stability Control, rely on it. In case your vehicle has these systems installed, then they might not be able to function as intended if there is a major fault in the ABS module.

What are the possible causes of a fault in the ABS module?

The ABS module is one convoluted system, and that can make debugging the source of the problem a mind-numbing task. The following list covers the major reasons behind the failure of the ABS module and aims to make things a little easier for you.

  1. Defective Speed Sensor – A faulty or unresponsive wheel speed sensor can trigger the ABS warning light to come on.
  2. Damaged Hydraulic Pump – Hydraulic pumps, like most pumps, are susceptible to damage and the cause of this could be due to internal wear arising from poor quality brake fluid or the lack of brake fluid.
  3. Clogged Valve – A clogged valve will prevent the system from modulating pressure to the brakes.
  4. Controller Malfunction – The controller is the heart of the ABS module. If the controller stops working, it will cause the entire system to shut down. Other systems like Traction Control can come to a halt due to a problem with the controller.
  5. Brake Fluid Anomaly – The ABS relies on the brake fluid to regulate the pressure in each of the wheels. In case you have forgotten to refill your brake fluid reservoir, it can cause the ABS to malfunction. Using the wrong brake fluid can be troublesome as well. You should always check for the proper brake fluid before changing it.
  1. Faulty Wires – The wires connecting the various functional parts of the ABS module could be damaged, and this will result in the malfunctioning of the system. Corrosion in the cables can be yet another cause for system failure.

How can I diagnose and fix the problems with the ABS?

If you avoided reading the section involving the components of the ABS module, you could skip right ahead to the 5th and final step in this list. On the other hand, if you are adept at fixing small mechanical problems of your car do read through the following steps.

Step 1 – Remove the wheels of your vehicle and check if there is any notable damage to the speed sensors or the wires connecting the sensors. If you can’t notice any visible damage, it’s best not to meddle any further. If you can’t locate the speed sensors inside your wheel hub, it means that they are located inside the transmission module. You are pretty much out of luck if the actual problem is with your speed sensors.

Step 2 – Now that the wheels are already off, you can check the condition of your brake fluid. Replacing the brake fluid isn’t an overwhelming task, in fact, you can easily do it with the tools lying around your house. If you plan on changing the brake fluids on your own, I will suggest you watch this YouTube video – www.youtube.com/watch?v=V5O_pbC8R2E, before you get started.

Step 3 – If there is no fault with the speed sensors and the brake fluid, your next step would be to check the ABS fuse. If you can locate the fuse for your ABS, check whether it’s blown or not. However, just replacing the blown fuse is a temporary solution. The fault which caused the blown fuse is still not fixed.

Step 4 – At this point, if your ABS light problem persists and you are adamant to fix it yourself, the final option would be to check for the ABS trouble codes manually. For that, you need to locate your car’s data connector first. After you have found the car’s data connector, you need to follow the correct procedure for your vehicle to transmit the ABS trouble codes manually.

In most cases, you will need a jumper cable to connect the two distinct terminals of the data connector. This will send the onboard computer into a self-diagnostic mode and make the ABS light flash. You can determine the particular code by counting the number of times the light flashes. However, this crude method can be prone to errors.

Step 5 – If you are like me and you find these processes extremely tedious, then I would suggest you consult your trusted mechanic or your authorized car dealer. As mentioned by https://www.yourmechanic.com/services/abs-light-is-on-inspection, a typical ABS inspection cost will be around the $80-$100 range. This doesn’t include any parts replacement. Also, the price may vary according to the type of your vehicle.

How do you maintain your vehicle’s ABS after repairing?

After fixing your vehicle’s ABS, it is important to maintain it properly so that it remains functional for years to come. The following are some of the measures you can take to ensure your vehicle’s ABS stays in tip-top condition:

Avoid Spraying Water at Your Wheels – Speaking from experience, you must avoid spraying excess water at your wheels, while cleaning your car. Use a slightly wet cloth to clean your wheels instead.

My 2015 Honda Fit’s brakes went into a berserk state soon after I started spraying my car’s wheels with a hose. After consulting the authorized dealer, I found out the source of my problem and ever since then I have always taken extra caution while cleaning my vehicle.

Remember to Change Brake Fluid – Typically cars require brake fluid to be changed every 30000-40000 miles. However, you should consult your owner’s manual to find the appropriate range for your vehicle. Do set a periodic reminder so that you don’t forget to inspect your brake fluid condition every year or two.

Improve Your Driving Habit – Avoid using excessive braking to stop your vehicle. When you are approaching a stop signal, stop accelerating and let the surface friction do most of the work. Gently apply the brakes at the end to bring your car to a standstill. This will not only ensure longevity for your ABS but also improve your vehicle’s fuel economy.

If you have reached till this part, then kudos! I highly appreciate the time you have spent in reading this article. Hope you are now well prepared to tackle your car’s malfunctioning ABS. I wish you all the best with your repairs and do remember to maintain your vehicle properly to avoid such sticky situations in the future.


About the Author Roger

Roger is a mechanical engineer by day and grease monkey by night, who spends all his free time tweaking things in his car. His love for car audio equipment is only matched by his desire to help others find the best products suited to their needs.

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