Left Side Trailer Lights Not Working on Multiple Trailers Being Towed By 2007 Ford F-150

Updated 11/08/2012 | Published 11/06/2012

Question:

I have the same problem with all my trailers, so I think its the truck. I even replaced the OEM 7 pin and 4 pin trailer wiring harness on my 2007 Ford F150 to try and correct the problem. My left turn signal, left brake light and running lights do not work. The only thing on both 7 and 4 pin plugs show power in the right rear brake light and turn signal, and the electric brakes work.

asked by: Ray S

Expert Reply:

On your 2007 Ford F-150 I would start by checking the relay fuse box located under the right hand side of the instrument panel inside the cab. There are two 10 amp fuses in the box that protect the trailer towing lights. The fuse at location number 36 is for the right side lights and the fuse at location number 42 is for the left side lights.

I would also recommend to check your owners manual to determine if you are missing any other fuses or relays that are required for towing a trailer. There could also be a fuse box located under the hood of the vehicle on the drivers side that could contain relays or fuse

If all the towing fuses are installed and working properly you will then want to check the wiring behind the vehicle connector on the vehicle to make sure that there is no break or short in the wiring.

expert reply by: Jeff D