I have a 2004 Avalanche, it will automatically go into 4 wheel drive. I have had problems with it previously when putting it into 4-wheel drive and couldn't get out of 4 wheel drive. Finally, after getting it out, I took it to the shop and tey recalibrated the transfer case. Now it will go into 4 wheell drive automatically and the red light came on for the 4 wheel drive. What do you think the problem is? Thanks for your help.