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Why Your Brake Light Turns On And How To Fix It (2021)

April 21, 2021

When your dashboard brake light illuminates, it’s a sign that something’s wrong with your brake system. 

But what can trigger the brake warning light? 

And what should you do? 

In this article, we’ll explore everything about dashboard brake lights. 

From why it turns on to the easiest way to get any brake light issue fixed.  

This Article Contains

Let’s get started.

What Is The Brake Light?

In most cars, the dashboard brake light is the light on the dashboard with an exclamation point (“!”) inside of a circle. In some cars, it’s a light that has the words “BRAKE” spelled out. Whenever it turns on, it’s usually a sign that something’s wrong with your brakes.

Sometimes the brake warning light will turn on alongside other brake-related lights, like the:

But why is your dashboard brake light on in the first place?

6 Reasons The Brake Light Is On

Here are the most common reasons why your brake warning light is on:

1. An Engaged Parking Brake

This is the most common reason why your brake light is on. 

If the parking brake is still active, the parking brake sensor will prompt the brake warning light to turn on. This usually happens when you don’t fully disengage the vehicle parking brake, and the solution is to simply disengage it completely.

If you leave it as it is, you’ll be driving around with active parking brakes, and doing so will not only overheat your brakes but accelerate brake shoe and brake pad wear. 

These increased temperatures can also speed up brake fluid degradation, affecting the efficiency of your braking system.

2. Low Brake Fluid Levels

A sensor in the brake master cylinder monitors the brake fluid level in the system. If levels are below the minimum threshold, the sensor will trigger the brake light to illuminate.

Low brake fluid levels can be a major cause for concern as it can indicate a brake fluid leak which will need addressing ASAP.

3. Worn Out Brake Pads

Worn brake pads can also cause a drop in brake fluid level as the caliper pistons have to reach further to contact the rotor, which can also trigger your brake warning light.

This can also be down to the sensor wire on your brake pads.

Once the brake pads are too worn, this sensor wire contacts the rotor and forces the brake light (or brake pad warning light) to light up.

4. Anti Lock Braking System Malfunction

Most vehicles equipped with an antilock brake system (ABS) have an ABS brake warning light. 

Problems with the antilock brake system can trigger both the brake warning light and ABS light (if it has one) to turn on. Causes can range from an electrical malfunction to something as simple as a dirty wheel speed sensor. 

When this happens, have an auto professional review your ABS codes to determine the issue.

5. Defective Sensors

Throughout your vehicle, there are many sensors linked to the brake system, such as the sensor in your parking brake, master cylinder, or the ABS. When they malfunction, they could trigger your dashboard brake light to turn on.

6. Faulty Rear Brake Light Bulb

Some car computers monitor the rear brake light bulb, which could be a single light bulb or even an LED bulb array.

If a bulb goes out or dims, it may cause the brake warning light to turn on. This is especially helpful as drivers are often unaware that their rear brake lights aren’t working, and this can help prevent rear-end collisions.

While you can swap the rear brake light bulb yourself, it’s better to get a mechanic to do it as each vehicle may have a different light bulb type and varying bulb socket access.

Now that you know the potential causes, what should you do when the brake light turns on?

What Should I Do If The Brake Light Turns On?

Here’s what you should do if you notice an illuminated brake warning light in two different situations:

1. The Dashboard Brake Light Turns On Before You Drive

If you haven’t begun driving, check your parking brake and make sure that it’s completely released. 

If the brake light stays on even after you release the parking brake, you can check the brake fluid level and consider topping it off if it’s low. It’s best to get your mechanic to do this because your brakes may need to be bled of air

2. The Dashboard Brake Light Turns On While You’re Driving

If you’re driving and the brake light turns on, pay attention to your brake pedal. If there’s a brake fluid leak in the brake system, your pedal response may feel different. You can always stop at the first safe spot you find and then check the brake fluid level.

If it’s an emergency and the brake fluid level is low, you can top it off (if you have fresh brake fluid on hand). However, it’s still important to get your vehicle to a mechanic for a brake checkup as soon as possible.

Notes on a brake fluid top-off: 

Since there’s so much to keep in mind, it’s always better to let a mechanic handle this for you.

Speaking of mechanics, how do you fix these brake light issues?

An Easy Fix For Your Brake Light Concerns

You don’t want to be driving around with a faulty braking system, so it’s always better to have a reliable mechanic come to you whenever there are brake issues with your car.

And to do that, all you need to do is contact RepairSmith.

RepairSmith is a convenient mobile vehicle maintenance and repair solution, and here’s why they’re your best option:

What about the cost?

As the cause of an illuminated brake warning light can vary, so will the repair costs. 

For an accurate estimate of what your brake system repair will cost, simply fill out this online form.

Now that we’ve covered the basics of brake lights, let’s go through some FAQs.

5 Brake Light FAQs

Here are a couple more answers to some brake light-related questions you have.

1. How Do Brakes Work?

When you depress the brake pedal, the force from your foot is converted into hydraulic pressure by the master cylinder and pushed through the brake lines

The brake hydraulic pressure is conducted through the brake fluid (in the brake line), engaging the brake mechanisms. 

The exact braking mechanism can vary based on your car.

It could either be brake calipers that clamp the brake pads onto the rotors (in disc brakes) or wheel cylinders pushing brake shoes on brake drums (in drum brakes). 

2. How Do I Verify If The Brake Light Is Working?

When you turn on the vehicle ignition (but before you start the engine), each dashboard light should light up for a few seconds. 

This is designed to help you verify that each warning light is operational before you start your journey. If some don’t illuminate, it means there’s likely a problem.

3. How Can I Check The Brake Fluid Level If The Brake Light Is On?

Your best option is still to leave this task to a mechanic.

However, if it’s an emergency, you can do it yourself — carefully. 

First, ensure that your car is in a secure and level location before you pop the hood to check the brake fluid level.

Locate the brake fluid reservoir

It’s often at the rear of the vehicle engine near the firewall — on the side where the brake pedal is positioned. Many brake fluid reservoirs are translucent, so you can quickly check the fluid level against a clearly labeled “FULL” (or “MAX”) line without removing the reservoir cap. 

However, if it’s not translucent, pop the cap, and you’ll be able to check the fluid level from the inside of the reservoir. Never leave the brake fluid reservoir open any longer than necessary, as moisture in the air can contaminate the brake fluid. 

4. How Can I Check If The Rear Brake Lights Are Working?

Reverse your vehicle close to a wall and press the brakes. You should see a red glow on the wall if your rear brake lights are working. If there’s no glow, you might have a problem with the brake light switch or a blown fuse.

It’s also a good idea to ensure that all your car lights are working while you’re at it. 

To do this: 

If there’s a problem with either of these, get them fixed ASAP as it can affect your road safety.

5. How Is The Rear Brake Light Bulb Changed?

Some vehicles have different signal bulbs for the turn signal and the brake light. 

Others may have a single light bulb with two filaments inside — doubling as the turn signal bulb and rear brake light bulb. 

To replace your rear brake light, your mechanic would have to: 

Since there are so many steps involved, it’s always a good idea not to change your light bulb yourself.

Final Thoughts

If your glowing dashboard brake warning light isn’t resolved by releasing the parking brake, make sure to get your brake system checked as soon as possible. 

And to do that, you can always count on RepairSmithContact them, and their ASE-certified technicians will be at your door, ready to help!