I have researched this problem and cant find anyone that had the same problem I have. I'm getting ready to tow a trailer here soon and I was playing with the TBC and I was able to press the + button and the gain is all the way at 10.0, but when I hit the - button nothing happens. I cant lower it all and its stuck at 10. I even go thru the trailer settings and change the gain between low medium and high and nothing changes as far as getting it away from 10.0. Any solutions or suggestions I should check out? My truck is a 2016 and came with the max tow package installed from the factory.

 

Not sure if this is the problem but I'd start by giving both the truck bumper socket and trailer plug a good cleaning out with brake cleaner followed by a wash with contact cleaner. Then smear dielectric grease on everything.