New to this forum. I am having problems with no power going to the 7 pin trailer connector. When I hooked up the trailer there was no signal lights no brake lights. I checked the plug with an automotive test light and there is not power for the signals and brakes. I installed the relay that was given with the truck so that 12v will be available at the 7 pin connector. I tested the pin and there is 12v present. I thought it may be the wiring harness but with the 12v present I am not sure that it is the harness. Any idea about this problem?

 

The relay only provides, charging if the trailers batteries not power to the plug. Just a FYI.

But for starters is start checking fuses.

Wayne

 

fuse #9 relay#21 on 09 to 14 f150s look at them if there good take it in you might have to drop rear tire and see if you have a bad connection at the rear harness block connector