2nd gear start

[lp14255]

I have a 2008 3500hd duramax that I want to try a little sled pulling with. I need some help writing a tune for the TCM to make the truck start in 2nd gear with the tow haul on and 4lo only. Can someone give some pointers on what to change.
thanks.

[THEFERMANATOR]

The 4 low table is it's own table. Don't believe tow haul works when in 4 low. The indicator light will come on in the cluster for tow haul because the BCM has sent the tow/haul command, but once you go to 4 low it will change to the 4 low shift table. As to how to do it, I believe most reccomend moving the 1-2 shift speed to 0MPH at 50% throttle and above so it will shift to 2nd while you're boosting it up.