What are the three buttons on the dash for? 1) The number four with a down arrow. 2) diagram of four tires and transmission. 3) A car skidding.

That is the most idiotic diagram of transfer case system I have ever seen.

I'm going to use process of elimination here
Top one=2 wheel drive
Middle = 4 HI
Lower = 4 LOW
Press 2 HI and 4 LO together, your transfer case will go into Neutral(hence the neutral LED indicator). And if I recall, your gear selector must be in NEUTRAL before the T-case will go into neutral.

What Mike said ^^^^^^^

. . . gotta love GM for cheaping out on some and saving $0.69 per car by offering an option for no auto 4WD therefore one less button and a transfer case with one less thing in it. I bet doing this cost them $0.67 per vehicle just to have the option available, $0.02 per vehicle to have the optional control designed and stocked, and $56.78 per vehicle when people figured out they'd been cheaped out of that feature and bought another brand next time.