flannery395

Good day all
So new to the forum. Looking for some assitance on what might be causing TRAILER DISCONNECT on my 2015 XLT FX 4x4 with factory installed electronic braking system, 7 pin connector. Was out last week with a camper, (tried 2 different campers and both came back with same) and after connecting the pig tail from the camper, DASHBOARD stated Trailer Connected, did my lights check on the trailer, however, as soon as I made adjustments to GAIN/LOSS, came back trailer disconnect. The Trailer Status in the MENU would not show the GREEN, YELLOW, RED as you would be braking like it should. Came back and last Sunday the 12th, connected up a MULTIMETER and Noticed that the ELEC. BRAKE PIN was only putting out 6.1 VDC. The TURN signals, and the POSITIVE were putting out 12-13 VDC. Curious to what might be going on?
Have others experienced this issue?
If so, what might the crowd recommend? Would like to avoid the DEALERSHIP as they want $175 just to run diagnostics.
Live in Colorado Springs, CO so if anyone is in this area and has recommended shops, that would be helpful too.

Gene K

It varies voltage according to speed. If I was guessing I would say you have a connection issue. Many have to duck tape the plug to the cover to keep a good connection because of the upside down cover I would put a good coat of dielectric grease on the pins then duct tape it to the cover and see if the issue goes away.

Lowrollin70gmc

I would first suspect corrosion in the truck side of the trailer connector causing an issue. Start simple and go from there. I like to clean them with a pick / small file and contact cleaner. Then, as the above poster mentioned, a coat of dielectric grease to keep future corrosion at bay. Even if this isn’t the issue, it’s good maintenance and nearly free.


Assuming the 6.1V was tested while the brake controller was not manually applied. A small current at the trailer connector is how the truck detects if a trailer is present. It sends a low voltage signal to detect the resistance of electric brakes between the brake pin and ground pin. So, 6.1 would be normal and I would continue further diagnostics on the truck and trailer (it is slightly possible both campers had wiring issues).

flannery395

@Gene K thank you for the information, I will climb under the Truck and take a look at the connection point and reinforce it to ensure good connectivity. Adding dielectric to my items to purchase to have on hand. Good information, thank you. Cheers.

flannery395

Thank you Lowrollin70gmc. Correct 6.1V was tested without the manual brake controller. Brake Pedal reading. Will get to cleaning the 7 pin connection. I visiually inspected it and does not appear to be any corrosion however, electronics are fusy and will clean and re apply dielectric grease. Thanks..Cheers

B-ManFX4

Curious what you find. I have this exact same issue and it is not because my connector is dirty. I cleaned it with Deoxit. It seems that it is related to the power brakes because one trailer has power brakes and the other does not but both have the 7 pin connector because both have back-up lights. The unit without brakes works as expected - the unit with the brakes behaves exactly as you described.

EDIT - Interestingly enough, even after I get the "Trailer Disconnected" message the trailer brake lights still function and the brakes work as well. I can manually activate them with the slider on the controller and feel them engage, as well as feeling them working as expected when towing.