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Maintenance

Tail Lights Not Working but Brake Lights Are – 6 DIY Fixes

Written by Nick Steiner

Nothing is more important than being safe while driving. If the tail lights are not working but the brake lights are, you and others are at risk. It is critical to have working tail lights, especially in storms, fog, or when it is dark.

A weekly check of brake and tail lights assures they are working and alerts you if there is a problem. A faulty tail light can get you a ticket or, worse, cause an accident. However, it only takes a few minutes to check and can save you money in costly car repairs.

How to Check the Brake and Tail Lights?

Checking the brake lights and tail lights takes only a few minutes. However, a weekly check will ensure both are in good working order. These weekly checks will also alert you to any other light-related issues and could save you a lot of money in the long run.

Have someone watch the backlights while tapping the brake with the car on. Both lights should come on. When one or the other is not working, it needs fixing immediately.  This is an easy, inexpensive fix; let’s look at six things we can check before calling a mechanic.

Tail Lights Not Working but Brake Lights Are: Easy DIY Fixes

Tail Lights Not Working but Brake Lights Are_ Easy DIY Fixes

Required tools

  • Flashlight
  • Screwdriver
  • Multimeter
  • Electric Cleaner
  • Soft rag

1. Blown fuse

When the electric current in the car becomes too high, the fuse is blown. This saves the electrical system from being fried. Fuses are color-coded; when removing a green one, replace it with a green fuse. The color refers to the amp rating. They are the easiest thing to check and replace.

The fuse box is in one of two places, inside the car on the passenger side near the lower part of the dash or under the hood in a black box with a lid. Check the owner’s manual if you can’t locate the fuse box. The manual will also tell you what the fuses are for; each one protects an electronic component.

Find the tail light fuse and remove it. Look for a break in the metal band if you find one; the fuse is no good. Head to the parts store and buy a replacement. Buy a multipack of fuses so you’ll have them the next time you need one! Pop in the correct colored fuse, and viola, tail lights.

2. Burnt out bulb

The most common reason the tail light is out is the bulb has burnt out. Turn off the car, grab a flashlight, and head to the rear bumper. Pop the trunk; there may be an access panel to twist the bulb and remove it. If not, remove the tail light cover and twist out the bulb.

Once you have the bulb, check the filament. If it is broken, the bulb is no good. If the bulb is gray or black, the bulb is burnt. Drop it in the garbage and head to the auto store. Bulbs are inexpensive, buy two, replace the one you removed and keep the other one in a dry safe place for use next time.

Older cars may have one light bulb with two filaments, one for each light; in this case, if one filament is broken, the bulb will need to be replaced. However, since most tail and brake lights have individual bulbs and fuses, you will only have to replace the bad ones!

3. Corroded socket

If the tail lights are still not working and the brake lights come on, look at the tail light socket. Moisture and corrosion can cause the connection from the socket to the bulb to be interrupted.

Remove the bulb and look for rust and corrosion, be sure to inspect the pins in the tail light connectors as well. Then, use the flashlight to light the inside of the bulb socket for better visual inspection. After inspecting, spray some electrical cleaner and place the bulb back in the socket.

Check if your car has a connector plug, use the car’s manual for this information. If the vehicle has one, follow the connection from the light to the brake light switch. Make sure everything is intact and connected correctly. If you find a break in the wiring or a poor connection that you can’t fix, you may need to have a mechanic look at this.

4. Ambient light sensor

The ambient light sensor senses when the light is getting dark enough for your lights to come on. If this sensor is dirty or not working, the headlights and tail lights will not come on at dusk or in a storm. This feature is in newer cars; check your manual if you are not sure you have a light sensor in the vehicle.

ambient light sensor

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You can check if the sensor is the issue by turning on the headlight switch. If the tail lights don’t come on when the switch is on, you need to check the sensor. The sensor is located on your dashboard top by the window.

Pop the dashboard cap near the window by sliding the screwdriver under the edge and popping it up. Next, slide the sensor out and check it for dirt. If it is dirty, wipe it off, pop it back in and recheck the tail lights when you flip the switch. The tail light comes on; it’s good to go. Still no tail light…you need a new sensor.

Take the sensor to the auto store; it will make it easier to get the right one (the part number should be on the sensor). Once you have the sensor, pop it in place, plug in the wire, and retest the switch to ensure the tail light is working. Make sure to refasten the dashboard cap before you leave the car. We should now have tail lights!

5. Faulty control switch

You may have a faulty control switch if all of the above is done and the tail lights still won’t come on, but the brake lights are working.  This switch controls the headlights, parking lights, and tail lights located on the dashboard.

The switch can be pulled from the dashboard and checked with a multimeter (instrument used to measure current, voltage, and resistance). If the switch is faulty, take it to the store for a replacement switch. The video below will show you how to use the multimeter properly.

6. Broken and corroded wires

We have done the checks on everything above and still have no tail lights; it’s time to check for bad wiring. First, check the manual; the wiring may run under the car from front to back. It may be the wire if the tail light doesn’t come on when pressing the brake pedal.

The first and easiest wire will be attached to the tail light socket; look for breaks in the wire, a loose, or a broken wire. If these are intact, you have to check the ground wire.

Check the manual to find the ground wire; use the multimeter to check this as well. Connect the multimeter to the negative battery connection, then touch it to an engine ground bolt. If you have a good ground connection, you will see it on the meter. If the ground is bad, replace the ground wire. If you are NOT mechanical, find a good mechanic.

All Ready to Drive Again!

While car maintenance is not always on our minds, making routine checks for the things we can fix ourselves will save money, keeping ourselves and other drivers safe. For example, when the tail lights don’t work, but the brake lights do, the chances of a ticket and accident increase. So fix what you can and know when to call a mechanic!

About the author

Nick Steiner

Nick has been a car nut for his whole life as far as he can remember. His father was a car dealer who used to change and repair his cars himself. As a result, Nick had the opportunity to get around all sorts of cars and learned to get his hands dirty repairing vehicles from an early age.

Nick is a great fan of Japanese quality and German preciosity. His deep passion lies in older models that he believes have a flair that takes him back to his childhood. He also loves their durability and reliability when compared to the modern models.

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