I have a 2005 F-150 with the tow package. I am towing for the first time with this truck, and am having problems with my trailer lights. The problem is with the truck not the trailer (the trailer lights work fine on my other truck). I used a test light, and am getting Left-Turn and Left Brake power, but nothing else(I checked both the four pin and six pin and got same results). Is this a factory wiring problem, or am I missing something??

 

I don't think you are missing anything, I could be wrong. I have the trailer tow package on mine as well. I have towed a boat and a flat top trailer, with no problems on any of the lighting with either. I would say it is a wiring issue on the truck. Was it added from the factory or from the dealer ? Did you say you checked the connections just at the plug on the truck ? Did everything work right there ?

 

It has the factory tow package...I checked both plugs on the truck and only have left turn and left brake (no right turn, right brake, no tail lights).

 

It sounds as though something was not connected right when they wired it up. Or either something has came loose. I would take it to the dealer and have them fix it, seeing as how it was installed at the factory.

 

I had the same problem with mine. I checked it when I got home with the trailer and the underside connector to the plug came loose in my hand. I pushed it back in and everything worked fine. I had the truck in for service at the dealer and asked them to check it. They said everything was working fine and maybe it was never plugged in all the way from the factory and I cured it when I pushed it in. He said sometimes the little clips don't always lock when not pushed in good. Try pushing the connector in on the backside of the plug. I have not tried it since then so I don't know if this permanently fixed it.
Good luck.

 

I had a similar issue couple weeks ago...Check your fuses inside the truck for the trailer. I had mine blown and ever since then, it has been fine

 

I would check your fuses and then your wiring. I would assume that would be the problem. Good Luck!