I will try and be simple and to the point. My electric trailer brakes are not activating. The truck is F350 super duty 7.3 diesel. The brakes on the trailer did work but after replacing the plug on the truck I think they stopped working. I also just replaced the brakes on the trailer. I have come to the conclusion that the truck is not sending any signal to the brakes to activate. I check all the fuses under the dash and they all checked out. The voltage coming out of the controller on the blue wire is reading 2 volts. I replaced the controller today and no change. The voltage never changes no matter what I do, depress the pedal or activate the trailer brakes with the controller. I am thinking this voltage should be changing as you apply the brakes or am I not understanding how they are activated. Is it current? The new controller is showing an error code saying there is a short in the circuit but I is shows this even when the trailer is not attached.

I am very reluctant to take this truck and trailer anywhere around here because I don't think anyone really knows how this system works. I have not searched this forum yet but that is next.

 

My 99 F250 has a 30 amp maxi fuse under the hood in one of the power dist boxes. Id look there and see if you have that as well and if its blown.

 

I check all the fuses and found one 7.5 blown but have no idea what circuit it was since ford does not label them. I don’t it solved the problem since I was still just seeing 2 volts on the blue wire coming out of the controller.

i went out tonight and reconnected all the wires in the plug to color match the wires in the trailer pigtail. When the running light did mot come on (they did before I started messing around today) I was about to give up. I turned on the left turn signal and the right tail light just lit up. The right turn signal flashed all the trailer lights. This told me things were f-up but maybe I could make it work. The red wire from the truck was definitely the running lights and i think it ended up on the trailer green wire. The green truck wire was the right turn and that ended up on the brown trailer wire. The brown truck wire ended up in the center which was the yellow trailer wire. The yellow truck wire ended up on the red trailer wire. I think the black stayed on black as did the white and the blue.

Prior to all this work tonight I had put things back together the way it was before I started or so I thought. Apparently not since the trailer breaks were now on and locked. Some how the running light wire must have been on the blue trailer wire.

when I test drove the truck and trailer the controller worked but maybe not as well as a more expensive one. It was a six break unit but it was only $35. When I tried adjusting the breaks every time I manually activated the breaks they just locked up, no matter where the gain was set. I drove around changing the gain and think it did start to lock up the trailer breaks when I hit the breaks but it was turned up all the way. In the past other controllers seemed to be adjustable using the manual control and the gain. I think they also had a sensitivity adjustment. This cheaper controller seems to be missing this addition adjustment. I have no idea how this mess came to be but somehow I think I must have had something to do with it when I changed out the truck socket.

 

Wish I could recall what brand I first bought for my 99 F250 but is IIRC it was a $58 teconsha one from E trailer. It was defective from the get go so dont rule out that possibility.