I have a 2011 2500HD with the 6 Speed Auto. I have a camper on it and will be towing a Jeep Wrangler behind it. I would like to know when to use M 3,2,1 or am I ok in tow haul mode with lever in drive?
George

 

Yeah just put it into tow haul mode and you are good to go. In tow haul mode the transmission ( I pretty sure) locks the clutches in so that don't have play in them. With a load and play in the clutches like regular driving, it will cause a lot of heat. Thats why you shift at higher rpms ( to not strain trans) and firmer shifts and if you let off and coast then press accelerator again the transmission will "grab" at higher rpms to keep you moving. I would not manually shift when you have a load, just put it into tow haul mode and you will be fine, that is what they designed it for. I hope this puts your mind at ease about how to tow your stuff.

 

Thanks Fishing and Mark. I figured the Tow Haul mode in drive would be the way to go. When would you use the 3 Manual positions on the shifter?
George

 

I've have used 1 or 2 when mudding so that i can be at high rpms and keep trans from shifting and bogging down. I guess the 3 can be used if you don't want to get into 4th to stay at a certain speed or rpms or something. I don't ever use 3