Tail light stays on when trailer is not connected to tow vehicle

[Gervaise]

On my right rear tail light the left 2 LED's are on. Trailer is not connected to truck, if I shut off battery, they go off....but why would they be on? Why are they getting juice from the battery and stay on?

 

[Silverado-FUN]

That is a weird one. Sounds like power from the trailer is back feeding the light . The system is separate from your Trailer 12 volt battery and should not effect one another. Wiring issue?. The first thing I would try is switching the light side to side if you can and see if there is the same issue with both lights. Silverado

 

[Gervaise]

Apparently it has to do with the breakaway brake system crossing over. I turned the battery off, and then on and the light did not come back on...