My trailer plug signal lights are not working. I have continuity from the power plug to the trailer plug and the lights work but I cannot get any power to my signal lights. I took the factory plug apart but found it hard to test for power because of the way the plug is made. All of the lights on my truck work correctly. Has anyone had any problems with the main factory plug at the back of the truck, where it splits off to the lights and the trailer plug? Again, all of the truck lights work correctly it is just the trailer plug signal lights that have no power. I would like a little input before I start tearing the wiring apart. It has to be in the main power plug, had problems then it started working again but now the signal/brake lights are not working at all. Has anyone bought a new female factory main plug?

 

I had issues with mine before and it ended up being a fuse. Each turn signal has it's own fuse for the trailer wiring, not sure about brakes and tail lights though. I'm sure they do as well. My lights on the truck were working as well. Might check those. Think they were on the passenger side kick panel.

 

Check fuses and take a ohm meter to The plug on your truck possible to have a wiring problem on the trailer. But most likely its a fuse.

 

I had a problem with my running lights on the trailer from corrosion cleaned it all up but nothing so I just cut out the the factory female plug and bought a new one from napa used those splicer taps to wire it and everything works great again. Does yours have corrosion or no?

 

There was no corrosion when I unplugged the factory socket, I had trouble getting my voltage tester to make contact on the female side of the plug, that is the side coming from the power. I did not realize that there were separate fuses for the trailer turn signals/lights so I will check my fuses. Thanks for the input, hopefully I can find the problem before I have to start cutting factory wiring.

 

The factory 4 pin connector on my truck does not have working turn signals but the seven pin does. Ford had put out a recall or service bulletin about the trailer harness years ago but I do not think it is still a valid recall.

 

It was the fuses, both turn signal/stop fuses were blown. Don't know when it happened, hopefully it was when I was screwing around with the plug or trailer and shorted them out and not an ongoing problem. I did replace bulbs on the trailer and did have some issues so it may have happened then. Thanks for pointing me in the right direction, even after all these years of towing I did not know or had forgotten that the trailer lights had separate fuses, guess we need refresher courses, lol. Anyway the good news is that I followed your lead and investigated before I started chopping wires.
P.S. Is it just me or did they design the fuse box to be accessed by a small person?? I am 6'1", 225# and had a heck of a time standing on my head trying to get the fuses in and out, even used a mirror to get them out, very hard to see the 42 and 36 fuses.