Trailer Lights Go Out When I Apply Brakes on Tow Vehicle 2002 Toyota Tundra

Question:

I have power to the lights on the trailer and they are wired correctly. But, when I step on the brakes with the head lights on, the trailer lights go out. Whats the problem?

asked by: Sam

Expert Reply:

It sounds like there is a bad ground connection somewhere on the trailer because your lights are working when they are not put under a load. Whenever your tail lights are on and then you apply the brakes, the system is under max amp load, and with a bad ground the lights cannot support all the amps. I would start by checking the ground connections of the tail lights on the trailer to make sure there is a good connection to a clean metal surface. You will also want to inspect the wires to make sure there are not any frayed or cut wires.

Also, if you have a plastic license plate holder behind the left side taillight that could be causing the bad ground connection as well. The brackets of the tail lights are mounted to the metal of the trailer and if you have a plastic license plate holder mounted there it could be hindering the ground connection.

I would also recommend checking the connector from the trailer to your vehicle to make sure there is not any corrosion inside the connector. I would also recommend just double checking the connector to make sure it is wired correctly.

expert reply by: Reno H