I have a 2006 F150 that is giving me grey hairs.

The problem... when I hook up my fifth wheel trailer 50% of the time I blow the fuse for the right signal light on the trailer, immediately!!!! The other 50% of the time it works fine and I have driven for hours without having a problem with the lights.

I went to my Ford dealer and had the wiring checked out and the service manager told me that all the wiring was fine but that that curcuit could be touchy so to make sure I have my truck and any power to the trailer plug (ie tail lights, etc) shut off when I plug in my trailer. I have tried this but still am changing 10 Amp mini-fuses like they are going out of style.

Any ideas or comments would be appreciated.

 

You probably have a chafed wire to the right brake/turn signal on the harness of the trailer.

 

I agree. It just about has to be a "momentary fault" kind of thing. You need to inspect the entire run of that circuit carefully. I bet you'll find some point where you can get a momentary short to ground.

- Jack