So i went to test out my new gooseneck connections in my bed and the trailer brakes will lock up about 6 inches after i move the trailer. Im not getting it. It did it on two trailers that i know work fine. The first trailer my truck was displaying a message saying check trailer wiring. After a couple minutes trying to figure it out my truck finally stopped recognizing the trailer and cut power to it. Is that a safety feature? Then the second trailer same thing move forward 6 inches and trailer brakes were applied for some reason. Why is my truck telling it to put on the trailer brakes. I took a test light to my 7 way and it appears to be good. When testing the 7 way is the 12V battery prong supposed to be hot at all times. Mine is but two trucks at work are not?
check the trailer wiring. I had a trailer that had the brake controller wire swapped with the 12V - locked up the brakes on connection to the truck - my truck also gave the 'check trailer wiring' message.
Yep thats exactly what Im having. The trailers i had all work with our F550 so im not real sure what the problem actually is. I went to a trailer sales place this week and they hooked my truck up to a box and my truck tested fine at both trailer hook ups so i know my trucks fine.
Does it only happen at the in bed plug or at the bumper plug also? Check for voltage with a digital meter at the brake terminal in the truck plug. These trucks send a reference signal( .1-.3 volts ) to verify a trailer connection. It's not supposed to be enough to activate the trailer brakes. I suppose it's possible for that signal to be corrupted and higher than intended.
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