Hello all,
My father has a 1998 F150 that has a problem with the hook up for the trailer. It is a factory installed 7 pin hook up. Recently he lost all the lights on the trailer and instead of checking fuses in the truck he figured that there was something wrong with the trailer and started checking that out first since some of the connection looked to be in bad shape. By the time he called me for help, the trailer needed to be wrung out and rewired correctly. After 3 hours of working on it I had gotten every thing to work right with it hooked up to my truck ( which also has a factory installed trailer towing package ). But when we re hooked it to his truck, the only thing that worked was the interior lights in the trailer. That is when I started going through his owners manual and found a blown fuse in the main box under the hood that controlled the clearance lights on the trailer. All the other fuses were good after checking them with a tester, but he still does not have brake or turn signals to the trailer. I am out of answers and was hoping someone could shed more light on this problem. Thanks Rob

Check the connections where the trailer harness connects under the rear bumper.

Then check the harness back to the power distribution box under the hood for any bad spots.

I did that with my name before: "Trebor Nedrah"

Have done all that all ready and found nothing wrong with any of it. Thanks for the suggestion though. Rob

Sorry I don't have anything specific for you I had a Gen 10 truck, but never had any problems so I never bought a repair manual. Have you tested the connector and harness itself? Maybe there are some relays in the Power distribution box for those circuits. I'm just throwing some ideas your way.

Yes did all that, you can now see why I am a little stumped over this one. Thanks again for trying, Blessings Rob

My brother had some similar issues with his trailer plug one time. He cleaned out the plug on the rear bumper real good then squirted some dielectric grease in it. Never had problems again.