vtchopperdude

Alright fellas, I'm stumped. I don't have trailer brakes. My 2012 has the factory TBC and I verified that both the fuse and relay in the underhood fuse box are in place, and good. I also verified that the kick panel trailer brake fuse was in place and good to go. My truck is the XL trim package, so it doesn't have the super fancy dash, but I can cycle through the SETUP menu, and it will show the trailer gain setting and if a trailer is connected. All trailer lights work and it's getting 12v power. I even used a 7-pin tester to verify it's not a trailer issue. When I plug in the trailer or the tester, the dash still shows "No Trailer" and when I use the manual brake slider, I get a message saying "Trailer Disconnected" on the dash. The trailer brake test light on the 7-pin tester does not light up when I hit the brakes or use the manual slider either. To me, this tells me the truck is not putting power to the 7-pin trailer brake wire. I have cleaned the connections, verified the wiring is correct, and done a basic inspection on the 7 pin connector wires. What am I missing here...???

Of note, I have auxiliary reverse lights tied into the 7-pin, using the reverse hot wire and the ground wire, so I know it's not a ground wire issue. Additionally, of note, when I was installing the reverse lights, I did notice that the blue wire (trailer brake wire) had been cut and spliced back together. The splice connection looked fine. I wonder why that wire had been cut previously.....? I bought the truck from Florida DOT, so I presume they purchased it from Ford with the TBC. But it still begs the question as to why that wire was cut at some point. Unless someone installed the TBC after the factory...but still, the fuses, relays, and Forscan programming was all done, so I'm just stumped as to why no brakes and the "trailer disconnected" message when the tester is plugged in.

I did read in another post about having to be over 20mph for the slider to work. However, that still doesn't explain why I'm getting the "No Trailer" and "Trailer Disconnected" message even when the 7-pin tester is plugged in. Thoughts?

Barry_Vee

IME “Trailer Disconnected” actually means brake circuit resistance is high.

Could be for a couple reasons. No trailer brakes attached would be one. A bad or poor electrical connection in a trailer brake circuit another.

Have towed several trailers with that message coming and going. When brakes were applied they worked, plus usually “Trailer Connected” immediately displayed.

Manual brake control on mine works without speed restriction. I also have aux backup lights powered from trailer b/u light circuit. Lights are tapped into wiring behind the receptacle.

Have never used a seven pin tester so won’t comment on what that is telling you. I do suspect it should have resistance equivalent to trailer brakes, in series to ground for the brake function.

2011 XLT Screw 4x4 3.5l 3.5LS

henfield

If you manually apply the trailer brakes ONLY using the slider do you feel them slowing you down? Is trailer verified as having brakes?