Brake lights only stick while parking or headlights are on

Hey everyone I'm hoping I can fi d out so.e answers here. I have a 2011 Freightliner Coronado with a Cummins ISX. I'm have trailer brake light issues. 8ve hooked to several trailers just to make sure the problem was in my truck. Whenever I have my parking lights or headlights on and I hit the brakes my trailer brake lights stick on. If I hit my marker interrupt switch or turn on my 4 ways the go off. The tractor brake lights don't stick 9n its only the trailer. Is this a wiring issue or a bad switch or relay somewhere? Thanks in advance for any and all help!
Justin.

 

Sounds to me like you have power back feeding across a circuit or a bad ground for a light causing a back feed.
This is causing the trailer brake light relay to stay engaged until you break the circuit.
Try breaking down the system. Unplug pigtail from truck and re connect. Unplug truck brake lights one at a time.
This is only a guess as I am not much on Coronados but where I would start.

 

I appreciate it I will try that.

 

The Columbias also had connectors behind the kick panels and behind the doors that could do stuff like that. Usually kind of green looking build up.