One of the guys on the Bass Fishin page has a 2003 f150 with the round plug. The center pin is for the back up lights that lets him back up his trailer but he doesn't have power to it when the truck is in reverse. My 2002 had the same problem ????
Thanks

 

There is a bag of parts that should have came with your truckwhen new. Ithink there are some relays and fuses. I had the same problem, I just figured that if the truck came with a towing package it would come ready to go, not so. Check in the bag there are instructions. If you can't figure it out e-mail me and I'll see if I can help. Good luck