Service Trailer Brake Message

[UPNorth45]

I have a 2020 Chevy trail boss and I cannot get the "service trailer Brake" message to stop appearing. That is the only light that is appearing, I have taken it to a dealership and a private shop with no avail. The trailer brake control module has been changed to the updated PN#85073615 with no change. Both shops have inspected the wiring harness with no discrepancies found. All of my trailer lights work but the trailer brakes do not. Any leads or ideas would be helpful. Thank you. 

[TheRiver]

Do the trailer brakes work when connected to another vehicle???

[UPNorth45]

Yes the trailer brakes on the trailer is not the issue I have tried multiple trailers. The truck itself is not acknowledging there is a trailer brake control module even in the vehicle. But the wiring harness has all checked out so far.