I´m new to this forum. I have a 2015 Silverado crew cab, LTZ Z71, 5.3 V8. Bought it new in Oct. 2015. Currently has 22,000 miles. Just recently started getting a Service Trailer Brake Controller code message. I have never towed with this vehicle. Live in chile, truck was built in Mexico. Noticed there is a service bulletin dealing with this same issue but dealer seems to think it can be fixed with a software upgrade? any suggestions on past experiences with this issue? other than that, truck has been perfect with no other issues to complain about. Thank you very much.