I have a the same truck and mine will not start and the truck will not move even in neutral. It cranks and the 4WD light flashes but no start and cannot get it to move no matter what.
Guys on other forum say I should disconnect motor on side of transfer case and then put it in neutral with pliers just to get in to a garage.
Wish I had known this was really a GM product when I bought it new! A repair every six months with this truck and the frame is as rotted as a thirty year old salt truck!