I have a 1998 F-150 that did not come with the trailer tow package. I installed a wire harness that plugged into the trucks wire harness along the frame by the spare tire. This harness had a 4 wire flat plug which I connected to the trailer. None of the trailer lights work however. We hooked the trailer up to another 1998 F 150 with that had a tow package and the trailer lights all worked fine. I am at a loss as to what to try next.
Any help!!!!?????

 

Get a test light and see if that plug has got power, I don't know right off had if it needs another fuse.....

 

The trailer tow fuses may also be missing or removed.
There will be one for trailer running lights as well as one for right and one for left turn/brake light.