I just bought a 97 expedition with the factory tow package. The vehical lights all work but I have no power to the trailer tail light prong. Everything else works fine. I checked the fuse and it is good. I also tried swapping the relays around in case that was the problem(my owners manual does not say what half of the relays are for). I bought a Haynes manual and it does not have a wiring diagram for the trailer tow system. I would apreciate any ideas, or if anyone knows where the tail light wire starts.

Thanks Kirk

 

Kirk , check the fuses in the underhood fusebox. The Vehicles lighting fuses are in the underdash box, and the Trailer Plug is fused independently at the underhood box.