Troubleshooting and Fixing "Trailer Disconnected" Message in F150
Recently, I was pulling our TT to our storage location and while applying the brakes and driving through a dip in the road, the dash lit up with a message that read "Trailer Disconnected". This had happened once before and it was due to the 7 pin cord not being completely seated and wiggling free from the connector. I pulled over and walked back to check the plug which was firmly seated. I unplugged it and plugged it back in but still saw the same message. Being only a couple blocks from my destination, I jumped in and drove to the storage spot.
While driving, I tested the brake control manually and it was not functioning. Once I arrived, I checked the lights and they too were not working. I reseated the plug several more times to no avail, tried to clean out the connectors as best I could but it would not work. A storm was blowing up and I had to get home so I headed out. I dreaded that this may be a grounding issue.
I called our TT dealer the following day to go over it with them and they suggested to check the fuses in my TV. If this didn't work, I was to bring it to them for warranty work if needed (this is an hour drive one way, no fun). I was doubtful this would be the issue as the brake controller and signals are all on different fuses. My suspicions proved correct in that no fuses were blown.
This monring I noticed a trailer in our parking lot at work that had a 7 pin wire and brakes. After getting permission, I hooked up to it and it too was not recognized by the truck. At least now I knew it was my truck and not the Jayco.
After 15 minutes of cleaning out my connector, checking fuses again, I happened to reach around behind the 7 pin connector (up under the bumper) and noticed the wire felt a bit loose. With the slightest of pulls, the wire unplugged from the back of the 7 pin connector. The wire harness on the back of the connector had shaken loose while braking through the dip in the road. I seated it (though frankly, it still feels pretty loose) firmly in place and now it works. I plan on applying some gorilla tape to it tonight to be sure the plug does not back out again.
So, if you have an f150 and experience a similar behavior, you too may have this issue.