What if your gmc sierra 2001 wont move when you shift into 4low you hear the gear engage but it dont drive are you doing somthing wrong?

Answer 1

Maybe it is locking more than one gear when it is put into low. It might not be releasing one or two gears are engaged at the same time the transfer case would lock up.You would have two different gear ratios trying to turn the wheels at different speeds and they would fight each other.