Tow/haul keeps your transmission locked up more allowing the exhaust brake to work longer. If TH is not enabled EB will disable sooner when the torque converter unlocks. The programming is different in my chassis cab verses the pickups and the 4.44 gearing also gives it a different experience, but you need try the different combinations to see which work best for your driving style and conditions. For my truck, EB will stay in which ever mode I select even after shutting down and restarting while TH will always reset to the off position. I am typically loaded around 15K lbs GVW and use EB Auto unless in traffic where I go to EB Full. When I have an additional 8K lbs in tow, I use TH with EB Auto unless I am in traffic or varying grades where I use TH with EB Full.
BTW: My EB icon is either yellow when set to Auto or Full or off when EB is is off - I do not get a green indication and have to look at the DIC to tell whether I am in Auto or Full EB modes.
