The lights on the plates, trailer connection will not work. I have checked all the fuses and replaced the ones that needed it, and with no luck still does not work. Need alittle advise.

 

Maybe bad wires? I'm not sure, but I think the trailer plug is directl wired from your tail lights. Are they working? Take a DMM to the trailer connection and see if you are getting the 13.8VLT from them. Report back.

 

the 4 prong connector for trailers is run off a different set of fuses, and they are located in the engine compartment.

https://www.fleet.ford.com/maintenan...ls/default.asp

according to the 2002 f150 in there, u need 2 replace fuses 5, 19, and 20 in the engine compartment.

hope this helps.

 

The factory trailer connector is NOT wired directly into the taillights. All circuits are isolated from the truck's lighting system to protect the truck's lighting from trailer wiring faults.

The original poster's symtom is unclear. Are the plate lamps on the truck or on the trailer (or both) the one ones that are out.

The truck's plate lamps are fed derectly off the truck's tail lights.

The trailer's plates and running lamps are fed via a relay in the engine compartment and are protected by fuse F1.5.

Fuses F1.19 & F1.20 protect the left and right brake/stop lamp feeds to the trailer adapter connector.