Terry Novak

I have a 2015 Silverado that I bought new. I have had the service trailer brake message off and on since new but the dealer says problem is in the trailer and not the truck. I can plug any one of several other trucks into my trailer and everything is fine. I now have no powere going to the blue trailer brake wire in the truck end of the plug,I have changed the dash control of the integrated system plus the control module under the truck bed . All fuses are fine. I did find a 2015 service bulletin from chevrolet talking about this very problem and zeroing in on circuit #47.Has anyone else had this problem with no help from chev? I cannot pull my 12000 pound trailer without brakes because I think it is definitly a safety issue. Any thoughts?