Was going to say most newer trucks are set up with a pigtail that connets either in the kick panel or under the column. I think Hopkins makes a kit. Something likw this. Worth every penny as far a making an easy install
2014-2017 GMC Sierra 1500 Trailer Brake Control Harness - Body Electrical - Hopkins 14-17 Sierra 1500 Trailer Brake Control Harness - 125150-03631533 - PartsGeek