Hope you have a suggestion for me. My 2003 F350 4 door 4wd with 5.4 L motor has a problem with the trailer plugs. Both the 4 pin inline and the 7 pin round will not bring on th e tail lights or running lights of any trailer or camper that i hook up to. i know the trailer wiring is good. Turn signals, brake
and flashers work normally but no tail lights. Don't have an owners manual but i pulled all the small fuses in the panel below and left of steering wheel but none were blown. I think that's the only fuse panel. Tail lights on the truck work fine. My Haynes manual is no help. I have a good digital meter but don't know how to diagnose the problem. any direction would be greatly appreciated.
JA: Have you checked the bulbs? Have you checked the connection?
Customer: Replaced bulbs on the small utility trailer but that didn't help. Hooked to a 28ft camper last night that had just been unhooked from my brothers truck and it was working for him. Pulled a 16 ft trailer about a month ago and all was well then.
JA: Are you fixing your F350 yourself? What have you tried so far?
Customer: Yes. Looked at the wiring underneath the back bumper. The wiring comes down in a flex conduit and then branches to the 4pin flat and 7pin round factory sockets Didn't see anything loose, broken or rubbed. Other than checking the fuses which were good, that's about all ive done.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Wish i knew more to ask but, nope , that's about it. And thanks for your help.