I just bought a 2015 2500hd LTZ..I have a 2019 coleman camper and a 2018 enclosed trailer..The trailer brakes have never worked when hooked to the camper and sometimes they work when hooked to trailer..I do know the brakes on trailer are worn out so I'm thinking that could be a problem on that but I'm puzzled by the camper..I borrowed a dump trailer from someone and the brakes worked great on that..I get a trailer connected message on dump trailer but not on camper..Also all of these worked with my old truck with add on brake module..thanks