This is what I have: 2004 f150 heritage, parker double axle trailer with electric brakes, the trailer also has a small motorcycle battery mounted near the front. I bought a brake controller and mounted it under the dash and plugged it in. The rear of the truck has a straight 4 pin and my trailer has the round connector (7pin). I bought a adapter. You plug the 4 pin into the adaptor run the blue wire up to the e brake modulator.....the purple is for back up lights (not used) the black wire is power and was told to run it to the battery bit did not......trailer lights were working in the parking lot but they are not working now when I got home.....any ideas?

 

Check the connections for the 4 pin. A 4 pin is not stock on these trucks as far as I know, so if someone spliced into the wiring I would check there.

 

Good call. I will check those wires when I get home. Currently I am only home 2 days out of the week.