So I have a 2000 Zr2 4x4 with the auto 4x4. When I push the button for auto or hi it just flashes. If i put it in neutral and go hi to low i can here it engage. Sometimes after pushing any of the buttons nothing lights up. But if you smack the dash they light up again, dont know if thats related but thought id let you know. Thanx Mike

 

Some blazers take a little while for 4x4 to engage. When I engage 4hi I'm usually moving, but not going over 25mph. For 4lo you may need to stop the vehicle, put it in neutral, then back into drive for it to engage. Sometimes you may have to push the 4hi button a few times for it to engage also. There is an article in the Tech section called "4x4 no worky"? that I believe will help you diagnose your problems. There are also several transmission and transfer case threads you can read that will help you.

Zach