what causes abs light to come on car
vehicle maintenance

What Causes ABS Light to Come On in Your Car?

One of the most crucial systems in your vehicle being constantly monitored by interior sensors is the car’s anti-lock braking system (ABS). This system closely monitors the wheels to ensure that each one is turning at about the same speed. 

However, if the onboard computer notices any abnormalities concerning the ABS sensors, the warning light in your car will come on, alerting you to a problem with your car’s ABS. 

Let’s discuss some of the details concerning this safety warning system, including what you should do when it lights up.

How Does a Car’s Anti-Lock Braking System Work? 

How a vehicle’s ABS works seems quite complicated to many of us, but it’s actually pretty simple. Typically, the ABS consists of four-wheel sensors. Sometimes, it may only be two or three. There’s also an anti-lock control module and a hydraulic one. 

If you notice that, as you start braking, your car seems to be going into a skid, your car’s ABS control modules will sense that either the wheels have slowed down or have stopped rotating. The ABS module will then apply assistance to help get you out of this situation. 

When skidding, you don’t have control over steering the car. But your car’s ABS module will take control of the brakes. Rather than keeping on braking, the ABS control modules will turn the brakes on and off. This helps you stop the skid. 

When Should You Get Your Car’s Anti-Lock Brake System Checked? 

ABS indicator switch on

As soon as you start your car, the ABS light will come on for around two to four seconds and then go off. However, if you notice that the ABS warning light is staying on, that’s the time to check your car’s ABS system.

It is perfectly normal for the ABS light in your car to come on briefly when you first start your vehicle’s engine. This tells you that the ABS is carrying out a check to ensure that everything is working correctly. 

If your brake warning light comes on when driving, you may find that the brakes still respond when you push down on the brake pedal. But you may not find you have as much control over the vehicle. 

When you need to carry out an emergency stop, you may lose traction control. At times like these, you should take your vehicle to the nearest mechanic for them to carry out tests to find reasons for the ABS light staying on. 

Reasons Why Your Car’s ABS Light May Come On

There are several reasons why your car’s brake system light would come on without any warning. Below, we look at the most common causes for an anti-lock brake system not working correctly anymore. 

1. Faulty Wheel Speed Sensor 

This sensor is found on the inside center of the vehicle’s wheel, or, in some cases, in the car’s transmission. 

These sensors are located close to the car’s braking system and are very vulnerable to getting damaged. Such damage is often caused by the amount of heat generated by the brake pads. 

It isn’t only heat that can cause such a problem. Pieces of debris from the road or metal shavings from the brake calipers and pads can cause them to fail. 

2. Hydraulic Pump or Valve Is Unresponsive 

When you push down on the brake pedal, the ABS causes a hydraulic valve to open to allow more brake fluid to be sent to the brakes. This will reduce the amount of friction that gets placed on the brake pads. 

This piece of equipment in your car is very susceptible to damage, often through wear and tear. One of the main reasons such parts fail is that the brake fluid inside has become contaminated with dirt. 

3. A Blown Fuse

As with any system or electrical component in modern vehicles, ABS brakes have a fuse. Check the ABS fuse box before you spend money on replacing expensive parts like the brake master cylinder or spend time troubleshooting. Look to see whether the ABS system fuses have blown or burnt out. 

Spending just a few minutes checking the fuses could save you a lot of money. Often in this situation, your car’s ABS brakes’ warning light will come on suddenly without any other strange occurrences. 

4. ABS Module Failure 

ABS module on car

There are several reasons why your car may have a bad ABS module, but the most common ABS failure of this kind is due to a problem with the wiring. Over time, water and other fluids can come into contact with the wiring, leading to data from the sensors on your car’s wheels being sent back to the ABS controller. 

Even a tiny amount of liquid coming into contact with the ABS wiring harness can cause it to corrode. And even a tiny amount of corrosion will diminish the car’s ABS controller powers. 

5. Brake Fluid Level Low 

All modern vehicles’ ABS modules rely on hydraulic brake fluid that gets driven through the brake wheel cylinder in order for the brakes to work. 

But, if there are insufficient amounts of fluid in the brake reservoir, this can lead to several problems when driving. The brake fluid level sensor will immediately notify the ABS controller, which leads to the ABS light coming on. 

If the brakes’ fluid level in the reservoir is low, the brakes won’t be as responsive. You may also find that it takes longer for your car to stop when you go to brake. 

There are a few reasons why the brake fluid level sensor would activate. 

  • Brake fluid is leaking from the reservoir because it has been damaged
  • The seal that helps to keep fluid inside the reservoir is damaged or rotten
  • Air has been able to get into the brake fluid reservoir 

6. Worn Brake Pads

Worn brake pads can cause the ABS light to come on. but it isn’t exactly because they’re worn. In around 90% of all cases where the anti-lock braking system light comes on, it isn’t a result of worn brake pads. 

The brakes on a car do not determine whether your car’s ABS system works or doesn’t. What is essential for you to remember is that a car’s ABS system helps control the speed of its wheels. Your vehicle will still stop even when the brake pads are worn down. This leads us to our next point. 

If you don’t replace this worn brake component and choose to brake more aggressively in response, then, over time, this can damage the vehicle’s ABS system.

One reason for the ABS light coming on in this case is that metal shavings from the brake pads can cause damage to the system’s sensors. 

The other reason for this is that worn brake pads cause brake fluid levels to go down quickly. The brake caliper piston is forced to move further away from the housing to get to the brake pads. 

Our Final Thoughts: What Causes ABS Light to Come On?

You should always know what’s going on around you when driving your car. As soon as you start to notice any abnormal brake noises or notice a problem with your steering wheel when you brake in normal conditions, it’s worth seeking out help from an experienced mechanic at a local auto repair shop.