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What Causes the ABS Light To Come On and Go Off

By Joe Ballard
Published on March 28th, 2024

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The first applications of the Anti-lock Braking System (ABS) were in the aviation and railway industries in the late 1940s. The goal was to increase the braking performance of heavy train locomotives and airplanes to increase safety.

What Causes the ABS Light To Come On and Go Off

The early systems worked well but were very expensive, so the challenge was making the ABS technology feasible for passenger vehicles. From the 1950s through to late 1978, the development of ABS technology was evolving in several countries, but Daimler-Benz in Germany was really on the cutting edge. The systems developed by Chrysler, Ford, and GM in the US and the systems developed by Toyota in Japan were effective.

Still, they were not ideal due to the limitations of hydraulic systems. To be fair, these early systems did improve safety, but mass-producing a four-wheel multi-channel ABS required a digital controller.

In 1978, the Benz team, led by Jurgen Paul, introduced the first four-wheel multi-channel ABS that used a digital controller. This innovation was a real breakthrough moment in the development of ABS technology. The system was not only capable of helping to avoid a crash but also opened the door for modern performance technology that is in use today.

In this article, I will explain what ABS is and describe what would cause the ABS light to come on and go off.

What Is an Anti-Lock Braking System?

ABS braking system

In a nutshell, ABS is a system that prevents the wheels from locking up when you brake to avoid skidding while maintaining traction. It is used in all types of vehicles, such as passenger cars, trucks, buses, and even motorcycles.

The modern ABS uses a computer to monitor each wheel's rotational speed change during braking. The computer automatically reduces brake pressure if the rotational speed slows too quickly (braking on a slippery surface) and the wheel risks locking up. Once the wheel rotational speed increases, the brake pressure also increases to brake the wheel slowly.

This process is repeated on all the wheels several times in a matter of seconds. That is why you often feel the brake pulsating when you brake hard. The ABS prevents you from locking up your brakes or applying so much pressure that the wheels stop turning while your vehicle is still moving, resulting in skidding.

ABS brake problems

In this scenario, you will lose control of your vehicle, which is dangerous when traveling at high speed.

A popular misconception is that the ABS will stop your vehicle faster. It is easy to understand why people believe this because when braking hard, the vehicle appears to stop quickly. In reality, the vehicle takes a bit longer to stop, but since it is a controlled stop, you have more control over the situation.

This allows you to avoid serious injury and increases the lifespan of your tires, brake pads, brake calipers, wheels, and just about anything else influenced by the braking system.

What Are the Main Reasons Why the ABS Light Would Come On?

Now that you have a better understanding of the ABS's inner workings, let’s look at some of the components in more detail and, specifically, what malfunctions would prompt the ABS warning light to come on and go off.

why is my ABS light on

The ABS warning light is an indication that something may have gone wrong with the system, and you need to take action to investigate it yourself with your OBD2 scanner or bring it into a service center for analysis.

If you are a DIYer, the Innova 5610 scanner is a great tool for analyzing the ABS and identifying the malfunctioning components. Here are some of the reasons that would cause the warning light to come on:

ABS module malfunction

The ABS shares several important components with another system in your vehicle. The other system is the traction control system, designed to keep all four wheels on the ground and rolling smoothly.

ABS module malfunction

If this system detects that one wheel is starting to spin, the system will cut power to that wheel until the wheel gains traction again. In this way, the system helps you avoid skidding out of control due to an imbalance of power in the vehicle tires.

Since both the ABS and traction control systems share the same control module and self-diagnostic system, they can sometimes interfere with each other. This situation may trigger the warning light to come on until the problem is resolved.

Low fluid levels in the brake system reservoir

The braking system uses the power of a hydraulic cylinder pressing against special brake fluid to cause the brake calipers to close the brake pads and bring your vehicle to a stop. There must always be enough fluid in your brake system reservoir to do this effectively.

If there is a slow leak in the system or the fluid evaporates, the fluid level will drop, and your brakes will not operate correctly. The computer module will detect this situation using sensors, triggering the ABS warning light to come on.

Checking the fluid level and topping it off as needed will usually resolve this issue.

The wheel speed sensor is malfunctioning

The wheel sensor provides the ABS module with information about how fast each wheel is spinning independently.

fixing a ABS light

If the module detects that the wheels are not all spinning at the same speed, then your traction control system will adjust the power for each wheel to compensate. If a wheel speed sensor malfunctions, it cannot relay information to the ABS module, and the ABS warning light will come on.

If you are a DIYer, you can use the OBD2 scanner to identify and fix the malfunctioning sensor or take it to the shop for service.

The ABS is turned off

In some vehicles, you may have the option to turn off the traction control or ABS. I have this option in my Hyundai Ioniq; however, I have never turned off the ABS.

Usually, when you turn off the system, an indicator light on the dashboard will turn on to warn you that this important system is now deactivated. If just the ABS or traction control light is illuminated, there is a strong chance that the system was turned off accidentally.

If you need to know where the switch is located, consult your user manual to find it and turn the system back on.

Conclusion

The fact that ABS has saved countless lives is indisputable, but not all vehicles are equipped with this very important safety system.

understanding why the ABS light goes on and off

In 2004, manufacturers were legally required to offer ABS in their vehicles, but it wasn’t until 2012 that all vehicles were required to have ABS. Older vehicles that do not have ABS are not required to upgrade, so there are still plenty of vehicles on the road without ABS. The warning light is critical for vehicles with ABS to ensure that the ABS functions properly.

Whether you are a DIYer with the tools and ability to identify and fix the issue or use a service technician to fix it, if the ABS warning light comes on solid or comes on and goes off, you need to take action to fix it. Taking prompt action will ensure you and your passengers survive a crash due to a properly functioning ABS.

Innova's mission is to simplify diagnostics for DIYers and mechanics alike. We encourage you to visit our community page or contact us if you have questions. We are always looking for ways to improve your experience.

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