Brake lights and taillights are often made from a single bulb, but they function differently.
Therefore, driving at night without brake lights or taillights can be extremely dangerous. The problem is that you often can’t tell if your taillights and brake lights are defective.
Therefore, it is necessary for the taillights and brake lights to work. But sometimes there are times when one of them works and the other doesn’t. Why then?
The most common reason why your brake lights don’t work, but not your tail lights, is a faulty bulb. It can also be caused by a blown fuse, a faulty brake light switch, or wiring problems.
Your vehicle’s taillights work fine, but the brake lights do not come on when you press the brakes. This is a strange problem since essentially all the connections for both lights come from the same source. Either one light shines brighter than the other, or the taillights go out completely when you hit the brakes.
Whatever your problem is, there is a reason for it and there is a solution.
Here is a more detailed list of reasons why the brake light is not working but the tail lights are:
5 Reasons Why Your Brake Lights Don’t Work, But Your Tail Lights Do
1. Defective bulbs
New cars often use LED lights for the taillights. But if you have an older car, you’ll want to check the bulbs.
The brake light and tail light often share the same bulb, but there are two different circuits inside. This makes it possible for one circuit to work and the other to burn out.
Replacing light bulbs is usually very simple and replacing them is very economical. However, if you want to measure them to make sure they are not dead, you can measure them with a multimeter or use an external 12-volt source to test them.
It’s unlikely that all three brake light bulbs will fail at the same time, but if you’ve been driving for a long time without realizing it, it’s very possible. There could also be a short somewhere that burned out all the lights if the wrong fuse was installed.
Especially if the brake lights don’t work but the third brake light works, chances are it’s just two burnt-out bulbs.
2. Bad brake light switch
A faulty brake switch is a common problem when your brake lights don’t work. There is a small switch installed on 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 it is pressed. It can also be the other way around depending on the type of brake switch.
3. Broken fuse or fuse box
All electronic equipment in a car is supplied with electricity by cables that pass through a fuse box. Modern cars have two or more fuse boxes. There is often one under the dash and one under the hood.
You need to pull out your vehicle’s manual and find the location of the brake light fuse. Most likely, due to an electrical overload, the brake light fuse has blown. Identify the correct fuse and replace it with a similar one.
In most cases, there is a reason why a fuse blows. If the fuse is blown, you need to make sure there are no shorts in the wiring harnesses or brake light connectors. However, in some cases, they can explode because they are old.
Remember to simultaneously check the fuse box for traces of water, which can cause short circuits in the fuse box that could cause a fuse to blow.
4. Defective plugs and connectors
There could also be corrosion on the taillight connector pins. Remove the taillight connectors and check for signs of rust or corrosion. Spray them with an electrical cleaner and reinstall them.
You should also check if there is a connector plug in the car between the brake light switch and the tail light. In some cases, there is a plug located on the floor of the car that has filled with water, causing corrosion.
Check your wiring diagram to locate the connector plugs in the car.
It is also possible that there is corrosion or rust on the sockets where the bulbs are installed. Check for corrosion and clean with an electronic spray.
5. Broken thread
In rare cases, there may also be a broken wire somewhere. This can be very difficult to find, as the wiring inside the brake light system can run from the front of the car to the rear.
A good way is to measure the voltage at the taillight when you press the brake pedal and do the same at the brake pedal switch. If one of the brake light switch wires is not receiving voltage, there is a problem with the power supply—either a fuse or a broken wire.