Thanks for posting. I have heard of the magnet trick for GM owners. I owned a 2011 Duramax with integrated controller and towed a fiver equipped with disc and a Titan pump. For that set-up, I had to use the Titan T4846000 module between the wiring coming into the trailer and the pump. Worked great.
On my current 2013 Duramax with integrated controller towing a Dexter disc equipped fiver with a Dexter pump, I had to use the Hydrastar Hba-Cam. Works well in this set-up, too.
From what I understand, the 2015 and newer GM trucks do not need either of these....but can't say for sure.
I love these forums...always good info from a lot of great folks.
Safe travels.
2018 GMC Sierra 3500 DRW 4x4 Duramax/Allison
2014 Lifestyle LS36FW
St Augustine, FL