I have an 08 tahoe i was wondering if these trucks auto shift into 4wd on their own... i have had it happen a few times to me. i was driving last night and it was snowing and i had the truck in auto... after a while i looked down and it was in 4hi i am pretty sure i didn't hit the knob with my knee or anything getting in or out of the truck and i know for sure that it was in auto.