This morning I pushed the 4wd button and while going through some snow, I heard a clunking and hammering sound about where my feet where. When I pushed the 2wd button it went away. This afternoon when I push the 4wd button, nothing, no front wheel power (like being in 2wd) I hear the click of the relay. No warning lights or messages on the dash
4wd problems on 2002 Chevrolet Silverado 2500 HD
i am having the same problem at first we thought it was in the front differential but after a closer inspection we found that i would lose the front end when we put it down on the ground it would pop out of 4wd at the transfer case
2 more answers
We just added this article last week, hopefully it will help you with your 4wd issue: http://repairpal.com/gm-4wd-warning-light-issues
Sounds like there is an issue with the transfer case. Get it to a shop and have it checked out before you get stuck without your 4wd. Good Luck!