Ran test today on the 7 plug on vehicle. Shows 12v, energized all time, no key in truck etc. Its leaving my passenger side light on the trailer on all the time. Any advice? Left, right turns signal work correctly, and so does brakes when vehicle is on.

 

It is my understanding that Hummer ran a datalink to the rear wiring harness to perform certain functions on the truck during production, therefore there will be a lead there that is hot all the time. My guess is that your wiring harness/adapter to your trailer is mis-wired to that lead, but shoot us a picture of the lead that is hot and we can confirm it on our trucks.