How To Diagnose & Fix Common Brake Light Problems? | Autance

Brake lights are an incredibly important part of your car that you need to make sure always work properly. They help to let the people behind you know you are in the process of braking and that they need to do the same thing so you don’t hit each other. There’s also the fact that…

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How To Diagnose & Fix Common Brake Light Problems? | Autance © How To Diagnose & Fix Common Brake Light Problems? | Autance

Brake lights are an incredibly important part of your car that you need to make sure always work properly. They help to let the people behind you know you are in the process of braking and that they need to do the same thing so you don’t hit each other. There’s also the fact that you can get a ticket for not having your brake lights on.

But the average driver isn’t a car technician. So, you might be wondering: How do I fix any problems I am having with my brake lights?

This is going to be a handy little guide to help you out while you are trying to figure this out. It’s helpful so you have an idea of where to start and what to do so you don’t need to pay hundreds of dollars to have it fixed. With that in mind, let’s begin!

What Effects Can There Be from Having Brake Light Problems?

Brake Light

First off is the obvious issue of other drivers not truly knowing when you are breaking. Whether your lights don’t come on or they stay on, this is an issue. This could potentially lead to accidents, especially at night if you are in an area with low amounts of light, like the freeway or backroads.

Secondly, modern cars have many different functions. Among these functions are the push-button start, anti-lock brakes and vehicle stability control. These are a few of the functions that will not work if the switch for your brake lights isn’t working properly.

If you depend on your car for functions like these, you will need to fix whatever problems your brake light is having as soon as possible.

How Do I Diagnose Brake Lights?

Before we start, keep in mind that you may need to use a volt ohm meter or an LED tester to test your lights.

Now that you have had time to make sure you have the tools with you or at least know what you will need to get for your car later.

The first step is determining what kind of system your car uses. If you have a more modern car, it may be using a digital sensor instead of a physical switch. If this is the case, you will need to take your car into the shop. You can check this by looking inside your car – or a diagram of your car if the user manual is lying around still – next to the brake pedal. Here you will see a type of rectangular shape coming off of the pedal assembly.

Typically, in a car’s electrical system, there is a basic two-wire switch that makes it function, similar to any other circuit of wires. One wire will control the power that goes into the brake lights while another wire controls the power that goes out of them. Take your LED sensor and place it on one of the two wires in your brake light. Hold the brake pedal down while you do this. Then test out the next wire. If the power is connected and your brake lights are working properly, the bulbs on your sensor will light up. If it does not, keep reading.

The next step you should take is checking the brake switch. To do this, you will need to remove the brake switch and have your volt ohm meter at the ready. You will also need the wiring diagram for your car. If need be, look up a user’s manual online and check it. This is important because it will help to show you which terminals on your brake switch you need to check. Some vehicles may have multiple switches on the brake pedal or have more than one set of contacts, which is why you should have a wiring diagram handy.

The brake-lamp portion of your switch should show continuity when the brake pedal is pushed down and an open-circuit when it is released. If the opposite is shown, then you will need to have the switch replaced.

There can also be other problems with the switch. This includes the brake pedal not contacting it because the small plastic pad between it and the brakes is broken or fell off and the switch has moved out of place. This is important because the brakes should push the switch to the full off position. If it is not making full contact, check for an adjustment.

Finally, you should check the lamp connections and the fuse. Make sure that all of the wires are properly connected to the brake lights. You should also make sure that the connectors are clean, don’t have any corrosion occurring, and that they are tight.

Check the bulb holder and make sure the bulb is fully in place as well as not burnt out. Also, check the fuse connecting the brake lights and the fuse box together. Take the fuse out and look at the wire that’s in the central window. If it is broken, replace the fuse with a new one of the same amperage.

What Are Some Common Brake Light Problems? How Do I Fix Them?

There are 2 common brake light problems that you can experience: having a burnt-out bulb or having a bad brake light switch. A burnt-out bulb would be why your light does not turn on as it no longer works due to a lot of use over the years. A bad brake light switch is a problem because the light switch is what turns the bulbs on in the first place. Having a faulty one will cause the lights to not turn on.

You can also have a blown fuse or a bad socket. But these are not as common to experience.

But How Do You Fix These Problems?

For a burnt-out bulb, check your user manual to see how to access your brake lights. Then you can safely remove the coverings and take out or unscrew the bulbs inside the brake light housing. Replace them with brand new bulbs to ensure that they last longer.

For a bad brake light, there are a few more steps you need to take. I’ll list them out because it takes a bit more effort than the other methods we will cover.

  •     Disconnect the battery. Disconnecting your circuit from the power is important to do whenever you are going to work on electrical equipment to make sure you don’t shock yourself. Use a wrench to loosen the nut connecting the ground cable and place the now free cable on the side of the battery.

  •     Put on protective eyewear, so you can prevent any debris from falling in your eyes as you are looking at the bottom of the dashboard and removing things.

  •      Find your brake pedal switch, which is above your brake pedal. Look at your user’s manual to find it if you are not entirely sure if you found the right thing or not. Once you have found the switch, disconnect the wiring pigtail – a single plastic piece that holds several wires in it – carefully by pressing down on the clip release and pulling it out by the plastic housing.

  •      Inspect the wiring within the wiring pigtail harness to see if there are any signs of it having burned or melted. If your brake light is permanently on, it could be because the pigtail was damaged. If it has been damaged, it needs to be replaced.

  •         Check the button of the switch to see if it pops back out once there is no pressure on it. If it sticks within the switch, the brake light will always be on. While having a friend look at the lights, see if this button affects the lights at all. If it doesn’t, the switch has gone bad or a fuse has been blown.

After all of this has been done and you have determined that you need to replace the brake light switch, here are the steps you take to install a new one.

  •    Make sure the wiring pigtail is disconnected and remove the switch from the brake pedal linkage. Vehicles mount their brake light switches differently, so if you can’t obviously tell how to remove it, look at the user manual. Be sure to keep track of all the parts.

  •   Slide the new switch into the same place the old one was in. You can also continue using the same mounting hardware as long as they were not damaged.

  •    Put the switch back on the pedal linkage and plug the pigtail back in. Also make sure to plug in any other connections you might have disconnected while replacing the switch, like the battery.

  • Test it out by turning the car on and asking someone to watch the brake lights and check that it works.

Replacing a blown fuse is also a bit tedious at times, but it isn’t too difficult a task. First, you need your owner’s manual or a manual online to find the right fuse box within your car and identify the brake light fuse or fuses. Next, disconnect your battery. Then use needle nose pliers and remove the fuse to see if the housing is clean inside. If it has been broken or burned inside, it must be replaced. If you can’t look at it, look at the ends for damage or burning. Finally, replace the damaged fuse or fuses with one of the same amperages and have someone help you check to see if the lights are working.

In the case of a bad socket that is dirty, has been corroded, or where the wiring has become worn, you simply need to replace the socket. In this situation, it may be best to simply go to your local mechanic who can replace it for you with the proper part and without ruining the frame of your car, or something similar to that.


Now that you have finished reading, hopefully, you have been able to identify the problem on your own! While it does take some time and effort on your end, the odds are that it is much more inexpensive when compared to going to a mechanic. However, if you are worried about replacing something incorrectly or it really needs a professional to fix it, like a digital brake switch sensor, then go to the shop.

Also, make sure to stay safe and re-check your lights once you are finished. Good luck and I hope your lights are up and running in no time once again!

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