Sometimes your brake lights may not work, but your tail lights will. When this happens, there could be a few reasons why, and many are simple fixes.
The reason your tail light will work but not your brake light could be due to faulty light bulbs, bad wiring, electrical grounding, or a blown fuse. Read on to determine the source of your car’s lighting issue and learn how to fix it.
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Are Tail Lights and Brake Lights the Same Bulb?
It depends. Some vehicle tail and brake lights share the same light bulb, but in some cars, they don’t. If you’re unsure whether your car’s tail light and brake light share a bulb, there’s an easy way to find out. All you need is a couple of minutes and a buddy.
One of you will watch the lights from the back of the car while the other presses down on the brake. You’ll be able to see which light in the assembly illuminates when the brake pedal is pressed. If it’s different from the tail light, they don’t share a bulb.
Are Tail Lights and Brake Lights on the Same Fuse?
Even if your tail light and brake light share a light bulb, they will have different fuses. The system needs two separate circuits to allow the car to know which light to illuminate and when.
The proper fuse will trigger and light the bulb when you press the brake pedal. Similarly, when your tail lights are switched on, a different fuse will communicate that to the bulb. Even if they share a bulb, the fuse locations are different and connect to different circuits.
Tail Light Fuse Location
Generally, you can find the tail light fuse in two locations. It will either be in the main fuse box under the hood of your car or by the front passenger side fuse panel. If you cannot locate your vehicle’s tail light fuse box in either location, check your owner’s manual to see where your tail light is.
Brake Light Fuse Location
You should be able to find the brake light fuse in the main power center of your vehicle, under the hood. Like with the tail light fuse, you can refer to your owner’s manual if you cannot find it under the hood.
Why Does My Tail Light Work but Not My Brake Light?
There are a few reasons that your tail light is working, but your brake light is not.
The Lightbulbs Are Malfunctioning
One of the most common reasons your tail light is working, but your brake light isn’t, is that the brake light bulb is not working anymore. This is typically the problem when your car has different light bulbs for the tail light and the brake light.
If they share a light bulb, they would both be out, but if that’s not the case, then you have another issue on your hands.
Your Brake Light Fuse Box Is Blown
If the light isn’t working, the brake light fuse might have blown. If this is the case, replace the fuse box and check to see if it’s working again.
The Electrical Grounding Is Bad
The electrical ground not working is another common reason the brake lights are not working, but the tail light is. When the electrical ground isn’t working properly, it can cause wires to corrode or damage, causing connectivity issues for the brake light.
The Wiring Could Be Damaged
Faulty wiring isn’t the first thing you’ll usually check. If the light bulbs, fuse box, and electrical ground are all working, then this is most likely the problem you’re facing. The wires could also be loose or worn out.
Your Turn Signal Switch Might Not Be Working
Last but not least, if your turn signal switch isn’t working, there’s a good chance your brake light isn’t working either.
The turn signal and brake light run through the same circuit in most cars. If your vehicle’s brake light and turn signal share a circuit, see if the turn signal on that side of the vehicle is working. If not, the switch is likely broken.
What To Check When Your Tail Light Works but Not Brake Light
Knowing the common reasons why your tail light is working but not the brake light is just the beginning. Now, you need to figure out which reason is causing your problem. You can check four things to find the source of the issue.
Lightbulbs
The easiest way to check if the light bulbs are working correctly is to eliminate any other issues, then replace the bulb. You can do this yourself, but be sure to have someone press down on the brake pedal to see if the new light illuminates before calling it a job well done.
Fuse Box
Use your owner’s manual to locate the brake light fuse box. You can test the fuse box by using a connected test light from any auto parts store, attaching it to the ground, then pressing each fuse end to the tester.
Someone must press lightly on the gas pedal to see if the test light illuminates. If it lights up, then the fuse isn’t the problem. If it doesn’t light up, then you’ll need to replace the brake light fuse.
Wiring
Look at the wiring of your car’s brake light switch in the fuse panel and the one that goes to the light bulb sockets. If these wires are loose or damaged, this is a sign that they’re the root of the problem.
Even if they’re not loose or appear damaged, they still could be, so getting a professional opinion if you aren’t positive is a good idea.
A common cause of damaged wiring in cars is rodents, so ask your mechanic what solutions they have to keep rodents out of your vehicle.
Electrical Ground
Testing the electrical ground of your vehicle isn’t complicated. You’ll need to ensure an accessory ground wire is touching some area of the car. If it is, it’s grounded. If it’s not, you’ll need to attach the ground wire to a rust and paint-free metal area.
A multimeter is a great tool to test the electrical grounding, or you can have a professional test it if you don’t have one or don’t want to purchase one.
Can You Fix Faulty Brake Lights Yourself?
For the most part, you can. If your brake light isn’t working because of a faulty bulb, you can easily purchase a new one and replace it yourself. Changing the bulb yourself will save you some time and money.
If your vehicle’s tail light and bulb share a light bulb, but the tail light is still working and not the brake light, then there might be issues with the fuse or something more complicated.
Unless you have mechanical or electrical experience, it’s best to hire a professional to ensure it’s done correctly and you don’t accidentally cause further problems.
Final Thoughts
It may seem odd to have a tail light working but not your brake light, but it’s a common issue that many vehicle owners face. If you notice that your tail light is working but not your brake light, there could be several potential solutions.
You can check for some of these problems on your own and even fix them, like replacing a light bulb. If the issue stems from something with the fuse, wiring, or electrical ground, however, it’s best to enlist the help of a professional mechanic to get your car safely back on the road.
