The tail lights on your car not turning off may seem like the biggest problem in the world, but it could actually be one of the simplest to solve. Many people jump straight to assuming that the problem is something major, such as an electrical short or a blown fuse, when it’s actually something small and simple, such as one of these three things: a broken brake light switch, faulty trailer light plug, or a broken wiring harness. Today we will discuss how tail lights wont turn off.

A Broken Brake Light Switch

If you notice your tail lights on when the car is off, there could be a few causes depending on the vehicle. This problem can be due to a broken brake light switch or brake light switch stopper, faulty trailer light plug, or broken wiring harness.

 A brake light switch stops power to your tail lights unless they're needed. This prevents burning out brake light bulbs if you don't have your headlights turned on, but it is separate from your ignition system so that power doesn't accidentally flow to them when you turn your car off and keys are still in an unlocked position, for example. If it breaks, your lights will stay on until you fix it.

A Faulty Trailer Light Plug

Check the trailer light plug and make sure it is plugged into the right socket. If this doesn't work, then you might have a broken wiring harness.

 The trailer light plug is simply a 15-amp fuse, which can be easily replaced at an auto parts store. With your key in on position, check that there is power coming to your plug by turning on and off your brights. A defective brake light switch or brake light switch stopper can also prevent you from having working brakes lights on an older model car.

A Broken Wiring Harness

A wiring harness is responsible for connecting the tail light to the vehicle. If there is a break in this connection, the tail light will not work. When checking for these types of problems, you will want to inspect for any signs of wear on either end of the harness or any cuts or tears that may have occurred.

 A broken wire inside of a harness is another common reason for an illuminated tail light. If you suspect that your wiring harness has become damaged in any way, you will want to replace it. A new wiring harness will allow your vehicle to start and run properly.