was working fine but now when i plug trailer in no tail lamps. brakes and turn signals work. and tail lamps work on truck but nothing on trailer.

is there a fuse??

 

As you mention your tail lights are working fine on your truck but your trailer light are out. You need to check for power at your plug this can be none with a cheap 12 volt tester light under $ 12.00 at most auto part stores. We know your ground wire is good because you have brake lights. Most likely you have a bad plug connection...I would start there first. If your plug show power when the lights are on then you would need to trace the power leads on your trailer for a broken wire.Your trailer should have no in line fuses for running lights. Good luck Robert

 

Or check the fuse. #38, 20A in the Central Junction Box under the drivers side dash.

For future reference, it's all in your Owner's Manual, which you can download if you don't already have.

https://owner.ford.com/servlet/Conte...ionalEventPage

 

their is separate fuses for the truck and trailer lights. like dchamberlain said look in the owner's manual at it will explain all of it. pages 208 to about 210

 

thank you. too dark out now to mess around. damned Ohio mud. suck giant elephant *****.

 

The first time I tried to use my 2001 F150 trailer light hookup, half the circuits to the trailer didn't work. Checked the OEM connection on the truck & found one of the sockets had completely disintegrated inside the plastic holder, there was no metal left, just a lump of turquoise colored crystalline material. Apparently the road salt ate it up before I ever got around to using it.

 

Yes, there are different fuses for truck and trailer...

 

It was fuse #38. thanks chamberlain and everyone else.