Blog Car Care Advice Why Your Dashboard Brake Light Turns On And How To Fix It (2023)
Car Care Advice

Why Your Dashboard Brake Light Turns On And How To Fix It (2023)

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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?
what should you do

In this article, we’ll explore everything about dashboard brake lights, from why it turns on to the answers to five related brake light FAQs

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Let’s get started.

What Is the Brake Light?

Your car has two different “brake lights”:

The first set functions as a signal to tell other motorists and drivers that your vehicle is slowing down or coming to a stop. The second one is usually a sign that something’s wrong with your brakes. 

Sometimes the brake warning light comes on alongside other brake related dashboard lights, like the:

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

6 Reasons the Dashboard Brake Light Is On

There are plenty of reasons why the brake warning light comes on, including bad wiring, faulty brake sensors, or a blown LED bulb.  

Here are the six most common culprits why your 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 or handbrake is engaged, the parking brake sensor prompts the brake warning light to illuminate. This usually happens when you don’t fully disengage the vehicle handbrake, and the solution is to simply disengage it completely.

If you leave it as it is, you’ll be driving around with activated parking brakes. Doing so will overheat your brakes, accelerate brake shoe and brake pad wear, and could cause a brake lockup.

These increased temperatures can also speed up hydraulic fluid degradation and reduce the efficiency of your braking system.

2. Low Brake Fluid Levels

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

Low fluid levels shouldn’t be taken lightly as it might indicate a leak in the brake line, 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. 

In some cars, once the brake pads are too worn, a sensor wire contacts the rotor and forces the brake light (or brake pad warning light) to light up.

4. ABS Malfunction

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

Problems with the antilock brake system can trigger both the brake light and ABS warning light (if it has one) to turn on. The 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 handbrake, master cylinder, or ABS sensor. If 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 red light bulb or even an LED bulb array.

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

While you can swap the rear brake light bulb yourself, getting a mechanic to do it is better, as each motor 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 handbrake and ensure that it’s completely released. 

If the brake light stays on even after you release the parking brakes, 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 leak in the brake system, your pedal 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 fluid level is low, you can top it off (if you have fresh brake fluid). 
However, it’s still important to get your vehicle to a trusted mechanic for a brake checkup as soon as possible.

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

5 Brake Light FAQs

Here are a couple more answers to some brake light related questions you may 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 Warning 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 — like a blown fuse or a worn out light bulb.

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 check the fluid level inside 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 (including the headlight, tail light, turn signals, and fog light) 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 light bulbs for the turn signal and the brake light (rear 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, get your brake system checked as soon as possible. 

Your warning light can come on for plenty of reasons, and you don’t want to be driving around with a faulty braking system. So it’s always better to have a trusted mechanic come to you whenever brake issues occur.

And to do that, you can always count on RepairSmith

RepairSmith is a convenient mobile vehicle maintenance and repair solution that offers:

What about the cost?
As the cause of an illuminated 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.

Once that’s done, our expert mobile mechanics will come to your driveway, ready to help!