transfercase on 2002 Chevrolet Avalanche 1500

my transfercase will sift to 4 high,2 high,but will not shift to 4 low it goes back to where it was before i pushed the button

try putting it in drive and give it a little gas while you push the button. mine got stuck in 4 low and did this to get it out.
3 more answers
On my Avalanche, it works best to place my truck in neutral when I am almost to a complete stop and then pressing the button to get the truck out, or in to 4-low. I know this works, since I just done it last weekend.
On my '99 Susburban I have to be rolling between 5 and 15 MPH and shift to neutral for 4 wheel low to engage.
put your truck in N and then press 4 low you will hear in engage when you shift back to D this will also safe you wear and tear on transfer case if you do the same for 4 high. 4 high is shift on the fly but it just lets things go smoothly if you take time to engage in N before you attempt any slick or rough roads.