2005 F250 V10. I've got 2 issues that I think are connected. Last time I pulled my 30' TT about a month ago I noticed that my brake lights were staying engaged when I was connected to the trailer. Just the tail lights, though, not the 3rd brake light. Blinkers work and 3rd brake light works as it should. I noticed again today that my brake lights were still staying engaged (they probably have been that way for a month but I never am behind my truck to see them). The lights are staying in regardless of whether I'm hooked up to anything or not.

Second issue is that my "Trailer Disconnected" warning light won't go off now. I used to occasionally get the warning when I disconnected if we had been towing a long way but it would always go off. Now it just won't go away even though I'm not connected to a trailer. This also started a month ago when I noticed the brake lights.

I've read some on the forums here and perhaps it's he brake switch. But I'm really clueless when it comes to electrical issues and any help is appreciated.

 

brake lights on.. most likely brake light switch is bad.

trailer disconnect is most likely dirt or water inside truck side 7 pin connector.

 

Installed a new brand light switch and nothing changed.

 

has any other electric work been done to truck lately?

otherwise a wiring problem... power from somewhere is getting to brake light wire.

 

Pull the 7 pin apart at the plug and inspect for the green fuzz.

 

another idea.

the battery charge wire connector is bent and making contact with brake light wire or connector . inside the Truck 7 pin connector.

or dirt. junk inside same.