Brake Light On: Common Reasons Why and How to Fix Them

What Is The Brake Light?

Simply put, if you see your brake light on, it is one of several warning lights found on your dashboard that alerts you to a potential problem in your vehicle’s brake system. Unlike other warning lights, which can be heeded with mixed degrees of urgency, the brake light is among the most important to address immediately. Your brakes are a critical vehicle system and you may be put in considerable danger if you allow them to become faulty.

The brake light is often one of the most recognizable warning lights on your vehicle’s dashboard. Depending on the age of your vehicle, the brake light is likely to take on several appearances.

In newer vehicles, the brake light is often an exclamation point surrounded by one or more circles. In older vehicles, the brake light will often feature the word “brake” or a combination of both icons. No matter what it looks like, the brake light is nearly always illuminated with a bright red light, indicating the immediate importance of its message.

Primary ReasonsYour Brake Light Comes On

Parking Brake Engaged

When you engage the parking brake (such as when parking on a hill or other incline), the brake light will come on. This is often accompanied by a sperate parking brake light.

In general, this iteration of the brake light is designed to remind you that the parking brake is engaged and that you should not put the vehicle into drive until it is disengaged. If you do so, you will risk damaging your brake pads and rotors.

Brake Fluid Low

In many vehicles, the brake light will come on to alert you that your vehicle is running low on brake fluid. Without brake fluid, your vehicle’s hydraulic brake system cannot engage correctly, which could lead to delayed braking or sudden brake failure. This problem can be addressed by adding more brake fluid, either on your own or with the help of a mechanic. 

Often, this alert is signaled as with yellow light, rather than red light. However, if the light shifts from yellow to red, you know that your vehicle’s brake fluid is critically low or empty.

Worn Down Brake Pads

Depending on the precise sensors featured in your vehicle, your brake light may also illuminate if the vehicle senses that the brake pads have worn down too far. This can precipitate or be related to problems with the overall brake fluid level. While it may appear at first that your brake fluid is low, this warning may in fact be caused by a worn brake pad.

The cost between these two repairs is noteworthy, so it is important to seek out a mechanic’s advice in order determine which problem your vehicle is experiencing.

Additional Reasons The Brake Light Illuminates

Anti-lock Brake System Malfunction

Many modern vehicles come standard with an anti-lock brake system (ABS) which is designed to prevent the vehicle’s brakes from locking up in adverse road conditions. Without a properly functioning ABS system, your vehicle may skid or hydroplane when you are least expecting it.

Of note, the brake light may also be illuminated due to a malfunction in the ABS sensors. In either case, a technician will be able to diagnose the precise cause of this malfunction and offer remedies appropriate to your situation.

If there is a problem with this system, your vehicle may signal you using the brake light. However, some modern vehicles use a separate “ABS” light to indicate problems with the ABS system. Consult your owner’s manual to learn precisely which warning lights your vehicle features.

Brake Light Burnout

Vehicles will often alert the driver to an imminent tail light burnout using the brake light. Though this may seem unusual, the tail lights are actually within the brake system because they are properly known as “brake lights.”

In order to check on the status of your brake lights, have a friend stand a safe distance behind the vehicle while you press down on the brake pedal. If either is dim or burned out, you should pick up and install a new bulb before driving the vehicle again. A mechanic is also able to complete this task, if necessary.

Battery Low

When your vehicle’s battery runs low, a variety of electrical systems tend to go haywire. One symptom of a low battery is a warning light turning on without warning or cause. If your brake light turns on, though you don’t notice any of the above problems with your brake system, the brake light may have been flipped on by a dying battery.

Battery replacement can be performed at home, though mechanics are often able to do it quicker (as well as recycle the old battery afterwards).

What To Do If The Brake Light Comes On

If the brake light illuminates while you are driving

If the brake light illuminates while you are driving, you should take note of the current road conditions and test your brake pedal reaction speed as soon as it is safe to do so. If you notice a delay or change in your brake speed, you should use enhanced caution while slowing down or stopping until you reach your destination.

If stopping or pulling over is not feasible in your current condition, you should continue to use great caution when slowing down or stopping. When it is safe to stop, do so on the side of the road and begin to evaluate the cause of the brake light appearance based on the tests provided above.

The first thing to do is to check and see if your parking brake is engaged. If it is, disengage the parking brake and the brake light should turn off. If the parking brake isn’t engaged, then it may be another issue.

If the light comes on while you’re hitting the brakes

If the light only comes on while you’re hitting the brakes, your vehicle may have lost pressure in the brake lines due to low fluid or a leak in the master cylinder. This would need to be checked by a mechanic. This can also cause the brake light to remain on constantly.

If you need new brake pads

Another issue that can cause the brake light to be on constantly is if you need new brake pads. Again, this would be important for a mechanic to check.

Finally, if it’s your ABS brake light on, and it goes off and on, then it may be a glitch in your system. Or, if it’s on constantly, it means your antilock brake system is failing. This is an important function of your brakes that helps control the vehicle in hard braking situations. It must be checked immediately by a mechanic.

No matter what, you should make an appointment with your mechanic as soon as possible in order to diagnose this potentially hazardous malfunction.

Conclusion

The short and long of the brake light is that you should take it seriously. Though a simple cause may be the culprit, the brake light is generally an indicator that a critical vehicle system is facing immediate trouble. Heed that warning seriously, especially if the brake light has appeared recently before. If your brake light illuminates, be sure to follow heightened safety precautions until you can properly test each potential cause. Don’t let a brake light go unaddressed for long. Doing so may lead to catastrophic consequences for you and others on the road way.