Mike Harbour

I have a come to the conclusion that my truck did not come from the factory with the trailer brake option and the previous owner added the controller to the dash thinking that was all he needed. It seems that the JL1 option not only includes the dash controller but also the programming to the computer and some wiring changes. I added an aftermarket brake switch with the harness that plugs in under the dash and I now have trailer brakes.

I bought a new plug for the trailer and installed it. I also checked the wiring to the brakes on the trailer which was good. Also checked the ground wire and it’s good on truck and trailer. The owners manual states that the gain on the ITBC can be adjusted with or without a trailer connected. When I scroll through the DIC menu it does not show any ITBC info at all. It’s as if the truck is not equipped with it even though the controls are present on the dash.

I just purchased a 2018 1500 crew cab and I have no trailer brakes. I have searched the web and read every post I can find on the subject. I have eliminated any problems with the trailer itself. They trailer brakes work perfect with my 2003 GMC. I have a good ground circuit so I’m not relying on the hitch for the ground. I am not getting messages through the ITBC at all. I have cleaned the male and female connectors and checked the 30amp trailer brake fuse which is good. Is this the only fuse for the ITBC? I am guessing that I have a bad brake switch or the module under the rear of the bed is bad. Any advice would be greatly appreciated.