Why Is The ABS Light On?

Why Is The ABS Light On?

Last Updated June 13, 2023 | Meghan Drummond

One of the many warning lights your car can use to signal that there's a problem is the ABS light. The ABS light is supposed to come on when your anti-lock brake system has become disabled or may not be functioning adequately, but like all indicators in your car, it can sometimes be triggered by events that aren’t actually a threat to your braking system.

When you see your ABS light, your mind may immediately jump to the worst-case scenario, but more likely than not it’s a minor issue that you can handle yourself.

Anti-Lock Brakes

If your car was made within the past two decades then there’s a near certainty that it is equipped with anti-lock brakes. Anti-lock brakes are supposed to reduce your chances of being in an accident by preventing your car from losing directional stability in the event of an “extreme braking” scenario (caused by a deer, ice, or distracted drivers). If you’ve ever had to slam on the brakes you know that sometimes you don’t come to an immediate stop. Hard braking can cause wheels to lock up and skid, causing your car to lose its orientation which can make an already dangerous situation worse.

Aerial view sketch shows how anti-lock brakes prevent skids
How Anti-Lock Brakes Work

ABS works by using a speed sensor to monitor the wheels speed and then using a system of valves in order to control the hydraulic pressure of your brake system. Essentially, the ABS system replicates a tapping pressure until the car comes to a halt (which it can detect with the speed sensor).

Part of this process is also controlled by the electronic control unit (ECU) of your car, which is what takes the inputs from the various sensors and translates them into calculated reactions to reduce your speed and keep you from skidding.

Obviously, it’s important for this system to work, and you don’t want to simply clear the computer code and then keep driving without knowing whether or not your ABS system is operational. Here are some quick things that you can check before venturing out on a costly visit to the mechanic.

Easy At-Home Checks

The first thing you’ll want to check is your emergency brake. If the emergency brake has not been completely released then it may still be active which would cause the ABS alert light. One easy way to check is to completely secure your emergency brake and then completely release it.

If your emergency brake is off and you’re still seeing an ABS light, then the next thing you should check is your brake fluid.

Brake fluid is what applies pressure to your brakes, which is critical for their functioning. To check your brake fluid, you’ll first need to find your brake master cylinder which should have a brake fluid reservoir on top. Clean the top of your reservoir before opening it to keep gunk from getting into your brake fluid.

Then, you’ll want to check the brake fluid color. Like most of the fluid in your car, brake fluid does go bad over time, and when it does it’ll turn a dark color. That’s a sure sign that you’ll need to take it to a mechanic to have the incredibly toxic brake fluid drained and disposed of before refilling it with new brake fluid.

If the fluid looks good in terms of color and viscosity, then you’ll want to check the fluid level. It should be roughly a half-inch from the cap.

Bleeding your brakes can also help to improve their responsiveness by working out any air bubbles that may be preventing them from working properly.

Our cars are basically computers at this point, and that means that they’re prone to some of the same errors and problems as a computer. In the case of ABS, it is possible that you have a blown ABS fuse. Fixing this is a little more complicated than flipping a fuse in your home.

To find your ABS fuse, look through your owner’s manual, which should give you a precise location. A visual check can sometimes reveal the issue if it’s due to corrosion or a piece melting from overheating. If none of those signs are readily apparent though you can check your ABS fuse with a test light. If it’s blown, you’ll need to replace the ABS fuse.

Other Components That May Trigger the ABS Light

The ABS fuse, brake fluid levels, and emergency brake are the most frequent reasons for why an ABS light will come on, but there are other common ones that you may need to get a professional to check out for you.

ABS wheel sensors are notorious for having issues, which makes sense considering they see substantial wear and tear. These can be checked at home if you have jack stands, a voltmeter, and a spare afternoon.

Mechanic checks sensor using voltmeter
Sensors Are Checked with Voltmeter

The ABS computer module is one of the more expensive reasons that the ABS system could be showing an error code, but you’ll almost certainly know if this is the cause of your issue since there will be a pronounced humming after you turn your car off.

Resolving ABS Light Issues

These are the most common issues for ABS light issues, but there are many reasons that your car may be trying to get your attention, and the ABS system is an important safety component of your car. If you’ve checked everything that you can and don’t see an obvious cause, then it’s time to go to a trusted mechanic and have them take a look.

Though many people put off seeing a professional about their ABS light, more often than not it’s a minor issue that can be easily resolved. You’ll feel a lot better when your dash doesn’t flicker with a constant series of warnings.

Image Credit: Popular Mechanics, Your Mechanic

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