The Ultimate Brake Light Bulb Repair Guide and Video

Got a brake light bulb out and want to repair it yourself? Anyone that drives a car should know how to do minor repairs with everyday tools such as this without going to a garage. In this guide we will show you how to replace and repair your brake bulb while testing the light socket wiring using everyday tools, plus you will have the satisfaction of fixing it yourself.

When replacing any vehicle bulbs use OEM replacement parts and sockets to ensure proper operation with a longer lifespan. Cheaply made bulbs tend to burn out more rapidly which requires a repeat replacement.

After testing you may need a replacement bulb or socket and basic tools you can get from Amazon or the local parts store when you are ready to begin.

There are basically two styles of bulb replacements which are; The brake lens needs to be removed to access the bulb, or the bulb socket can be removed by simply twisting it counterclockwise from the backside of the lens either through an access hole which is covered by a small plastic panel or through the trunk or lift back or hatch. We will show you both types in the following article.

First sit back and watch this video that gives you an idea of what you are in for before you begin. Then follow down the guide to pick up on additional repair tips and information.

Now Let's Begin the Repair

Tools and Supplies That Maybe Needed
  • Replacement bulb
  • Replace light socket with pigtail
  • Screw driver set
  • Socket set
  • Test light
  • Protective gloves and eyewear

Park the car on level ground with the emergency brake on.

Step 1

Have a helper step on the brake pedal to confirm which brake bulb is out; right, left or high center lights. If none of the lights are working then the bulb is probably not the problem, though I have seen where all of the bulbs have failed simply because they had gone bad in a close time frame to one other and the driver did not notice or was not informed of the problem by other drivers. When you see a person who has a stop light bulb out you should do the right thing and tell them.

Learn more: Brake Lights Not Working To begin you must determine which style of bulb replacement your vehicle has, this is done by inspecting the lens and looking for mounting screws which hold the lens to the vehicle which can be on the side of the lens. You may need to open the truck, hatch back, tailgate or lift back.

If no mounting bolts are found on the outside of the lens they will be located in the back of the rear body panel. You may need to pull back the truck liner or remove a few plastic trim pieces before these nuts or the bulb socket is accessible. If no access hole is available you must remove the mounting bolts and remove the lens to gain access to the bulb. In the case below an access hole was provided by the manufacturer which makes the job easier.

Step 2

Now that you have located the light socket and wiring harness its ready to be removed for testing and repair. On most American made cars and trucks this bulb has two jobs both for the brake light and the blinker indicator which will have three wires feeding the socket; brake, turn signal, and ground wire. On European and Japanese cars this job is handled separately which will have just two wires, brake light and ground.

Learn more: How to repair a blinker bulb

Step 3

Grasp the bulb socket and twist firmly counterclockwise, this will allow the socket to come loose from the lens. Sometimes they can be a little stuck in which case you can use a pair of pliers to help break it loose. 

Step 4

Once the socket has been removed it will expose the bulb which may have a burned mark or be a light blue color which indicates a leak in the glass, in either case the bulb is no good.

Step 5

Grasp the bad bulb and pull it from the light socket (some bulbs you will need to push down and twist counterclockwise) then match it to the new unit, they should match identically. Plug the new bulb in and have a helper push the brake pedal to see if it works, if it does reinstall it back into the lens and reassemble the plastic cover or trunk mat and you are all set. If the light is still not working after replacing the bulb or it is dull or dim then more repairs are needed, continue with the guide.

Step 6

This is where some testing is needed to repair a bad connection or broken wire. Start with a test light and secure the ground clip to a known good ground source such as a bolt or solid metal piece. It's important to get a good connection free from rust or paint because the test light depends on this conductivity to work correctly and give you a good test result. Wiggle the clip so the teeth of the spring loaded clip dig into the metal to ensure a good connection.

Step 7

Have a helper hold down the brake pedal, the remaining working brakes lights should be on. Use a test light to probe each of the brake light sockets feed wires, one of them should light up. If you cannot find power then access the opposite light that is working and probe the wires until power is found to confirm the test light is working.

Reasons for lack of power at the socket

  • Broken wire in the harness
  • Body control module BCM failure
  • Turn signal or multi function switch failure

At this point it is best to inspect the wiring harness and look for obvious damage such as a cut or wear mark indicating the harness has rubbed against a metal frame breaking the wire. If everything looks okay get a wiring diagram from an online repair manual such as Mitchell1 or you can search Google Images to test the BCM light output wire in much the same way. To test the multi function switch you must connect the test light connection clip to power and test the ground circuit through the turn signal switch.

On older vehicles not using a BCM to control the brake lamps, test for power through the turn signal switch, the color of the wire will be the same as it is at the socket.

If power is present at the socket and the light is still not working continue with the guide.

Step 8

If you have power at the socket the next step is to check the system ground. Attach a pointed metal object to the test light clip and probe the brake light feed wire and the ground wire of the socket, if the test light lights up the circuit is working and the fault is in the bulb socket connections. If the test light does not light up there is an open connection in the ground wire. This will make the bulb be dim, dull or not work at all. 

You can either make a new ground wire connection by cutting the wire and using a new wire to any metal part near the socket, or follow the wiring harness and look for obvious damage or cuts in the wiring.

Step 9

Next, remove the bulb socket and inspect the electrical connector for burned or melted terminals, if found this is caused by high resistance creating an open connection causing the bulb not to work. If damaged the connector with pigtail will need to be replaced which you can get from Amazon or from the dealer for about $35.00 bucks. With the foot off of the brake pedal cut the harness and splice in the new connector.

Step 10

Next, inspect the bulb socket; many times this socket will be subject to heat and corrosion. Manufacturers will install dielectric grease into the socket to help protect the connection, but with time this clear or brown grease will melt out and expose the connectors to the atmosphere causing rust or corrosion creating an open connection. Use a sharp object such as an exacto knife to scrape the connection clean. This with help the bulb terminals connect to the socket allowing the bulb to work again. If this socket is badly damaged it should be replaced to avoid premature failure.

Step 11

With all connections cleaned or replaced and the power and ground checked with any repairs made to the wiring or connections reassemble the socket and bulb onto the wiring harness. Have a helper step on the brake pedal to confirm the bulb works. Then reinstall the bulb socket back into the lens and replace the lens if needed.

Check out our brake light bulb repair forum where our online mechanics have answered thousands of questions.


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