Brake Lights Not Working But Tail Lights Are? (How to Fix)

The brake lights and tail lights often use the same light bulb, so how come my brake lights are working but not my tail lights? Let's find out!

Brake Lights Not Working

The brake lights and taillights are often comprised of one light bulb, but they work differently.

Driving during the night without brake lights or tail lights can thus be extremely dangerous. The problem is that you cannot often tell if your taillights and brake lights are faulty.

Therefore, it is necessary for both your taillights and brake lights to work. But sometimes, there are occasions where one of them works, and the other doesn’t. Why is that?

Why Are My Brake Lights Not Working But My Tail Lights Are?

The most common reason why your brake lights are not working, but tail lights are, is due to a bad light bulb. It can also be caused by a blown fuse, a bad brake light switch, or issues with the wiring.

Your vehicle’s taillights are working fine, but the brake lights don’t come on when you press the brakes. This is a strange problem since, essentially, the connections for both lights come from the same source. Either one light shines more than the other, or the taillights completely switch off when you press the brakes.

No matter what your problem, there is a reason for it, and there is a solution. Here is a more detailed list of why your brake light does not work but tail lights do:

1. Bad Light Bulbs

Rear Light Bulbs

New cars often use LED lights for the taillights. But if you have an older car, you want to check the light bulbs.

The brake light and tail light often share the same bulb, but there are two different circuits inside it. This makes it possible that one circuit is functional, and the other one is burnt.

Replacing light bulbs is often very straightforward, and they are very cheap to replace. However, if you want to measure them to be sure they are not dead, you can measure them with a multimeter or use an external 12volt source to test them.

That all three brake light bulbs have gone bad at the same time is pretty unlikely, but if you have been driving for a long time without noticing, it is absolutely possible. There could also be a circuit short somewhere that blew all the lights if the wrong fuse is installed.

Especially if your brake lights are not working, but the third brake light is, it is a big chance that it is just two blown bulbs.

2. Bad Brake Light Switch

Brake Light Switch

A bad brake switch is a widespread problem when your brake lights are not working. There is a small switch installed at your brake pedal to inform the control unit when the pedal is pressed, sending power to the brake lights.

You can test the brake light switch with a multimeter to make sure you get a connection when the brake switch is released and no connection when you press. This can also be vise versa depending on the brake switch type.

3. Broken Fuse Or Fuse Box

Broken Fuse

All electronic equipment in a car is supplied electricity through wires that go through a fuse box. Modern cars have two or more fuse boxes. There is often one below the dashboard, and there is one under the hood.

You need to take out your vehicle’s manual and find out your brake light fuse location. There is a high chance that due to an electrical surge, the brake light fuse has blown off. Identify the correct fuse and replace it with a similar one.

In most cases, there is a reason why a fuse is blown. If the fuse is blown, you should make sure that there is no circuit short on the wirings or in the connector to the brake light. However, in some cases, they can blow because they are old.

Remember to check simultaneously in the fuse box for any tracks of water, which can cause circuit shorts in the fuse box that might blow a fuse.

4. Bad Sockets and Connectors

Tail Light Connectors

There could also be corrosion in the pins in the connectors of the taillights. Remove the tail light connectors and look for any signs of rust or corrosion. Spray them with an electrical cleaner and install them again.

You should also check if there is any connector plug in the car between the brake light switch and the tail light. In some cases, there is a plug located on the car’s floor, which has been full of water, which caused corrosion.

Check your wiring diagram to locate any connector plugs in the car.

There is also a chance that there is corrosion or rust in the sockets where the light bulbs are installed. Check this for corrosion and clean it with electronic spray.

5. Broken Wire

Broken Wire

In rare cases, there might also be a broken wire somewhere. This can be a real struggle to find since the wiring from inside the brake light system might go from the front of the car to the rear.

A good way to measure the voltage is at the taillight when you press the brake pedal and do the same thing at the brake pedal switch. If you do not get voltage on any of the wires to the brake light switch, there is a power supply problem; either a broken fuse or wire.

FAQs

Is there a fuse for the brake lights?

Yes, there is often a specific fuse for the brake lights. So, if your brake lights are not working, it could be that this fuse has blown and needs to be replaced. You can usually find this fuse in the engine bay or under the dash. If you’re not sure which one it is, consult your car’s owner’s manual or ask a mechanic.

Are the tail lights and brake lights the same bulb?

The tail lights and brake lights are usually the same bulb. However, some car models have separate bulbs for the two functions. The brake light is usually brighter with a stronger bulb than the tail light to make it more visible to other drivers. If you’re not sure which bulbs your car has, check your owner’s or a repair manual.

How do I know if my brake light switch is bad?

If your brake lights are not working, it is a sign that the brake light switch may be bad. If you notice problems with the cruise control or a warning light on your dashboard, this is also a sign that the brake switch is bad. It is a relatively easy part to replace and the switch is located near the brake pedal.

How can you tell if a brake light fuse is bad?

The best and easiest way to tell if the brake light fuse is bad is to remove the fuse and see if it’s melted or broken. If it is, then the fuse is bad. You can also measure it with a multimeter to be sure.

Conclusion: Brake Lights Not Working But Tail Lights Are

Driving around without brake lights is actually quite dangerous, because the cars behind you won’t see when you hit the brake pedal to slow down. Therefore, it is very important to fix the problem as soon as possible. Fortunately, this problem is often quite easy to fix.

The most common reasons why brake lights don’t work, but tail lights are include:

  • Bad Light Bulbs
  • Bad Brake Light Switch
  • Broken Fuse Or Fuse Box
  • Bad Sockets and Connectors
  • Broken Wire

As you can see, there are a few different things that could be going on if your brake lights don’t work but your tail lights do. It is important to diagnose the problem as soon as possible so that you can get it fixed and avoid getting pulled over or worse, causing an accident.

Electrical problems can be quite complicated to diagnose and solve without any knowledge about it, therefore you may need to contact a mechanic specialized in car electronics and diagnostics if you have tried the simple things above.

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Magnus Sellén
Written by:

Magnus is the owner and main author of Mechanicbase. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.