Originally Posted by Dakota25

So go from one button to the next just keep hitting them? How do I know when to stop?

Originally Posted by collega

So when You press button wait for 2-3 seconds and you could hear how your Transfer Case Motor is changing your setting from 4HI to 4HI LOCK or from 4HI LOCK to 4 HI. You can see how your buttons light will blink several times on the new button( 4HI LOCK, for example) and after"will be permanent. So it means that your transfer case settings changed already. After that, in 2-3 seconds, you could switch it back to 4HI button that same way.
1. Press 4 HI LOCK button.
2. Wait for 2-3 seconds, until TC Motor will change your settings and flashing light on 4HI LOCK became permanent.
3. Press 4HI button.
4. Wait for 2-3 seconds until TC Motor will change your setting back( Listen for the sound of TC motor).
5. Repeat this procedure at least 20-30 times.
If your problem in this case, so it should help to fix it.
Do it when your truck is not moving.
Good luck.

Originally Posted by Dakota25

So did that. The light will flash but will not become permanent on any of the buttons. The all flash but nothing happens and it's still snows service 4wd

Originally Posted by collega

This switching of buttons is working just for 4HI LOCK button and back to 4HI. If you try to do it for 4LOW LOCK it will not switch in that mode, but in my case, when I switched from 4HI to 4HI LOCK and back lights first were flash but after became permanent. Try one more time. Light in 4HI LOCK should flush and after that be permanent. If it doesn't work, it means that something wrong probably with Transfer Case.

Originally Posted by collega

You should press middle button, second from the top. It said: 4HI LOCK on it. Don't touch round one. It's rear differential lock button! Also don't switch and touch to the lowest button! So, just press second button with 4 HI LOCK and after 5 seconds press back the first from the top button: 4HI. You should see how lights should change from one button to another one. Is it any clinging noise coming from your Transfer Case when you are driving?

Originally Posted by Dakota25

That didn't seem to work , however after driving the car several places I turned off and started when I left each place. When I started it up after my last stop the light on the 2nd button lit up and the service message went away. Kind of weird but I'll take it

Originally Posted by collega

Be sure that you are driving in 4HI mode! It means that your first from the top light should be on(4HI)! Don't drive in normal road conditions if your Transfer Case setting in 4HI LOCK and your middle button light is on right now! In this case your can damage your transmission, because this setting is just for severe off- road conditions( deep snow, sand, mud etc.) But if your TC settings in 4HI mode (light is on your top button 4HI- normal road conditions) and your warning message( Service 4WD) on your DIC( Driver's Information Center) disappeared, so it should be fine. Normally this message still could stays on for some period of time after you did those "30 Switches"and after next time you stop and start your engine should disappear from your dash board.

Originally Posted by Dakota25

So go from one button to the next just keep hitting them? How do I know when to stop?

Originally Posted by collega

I had the same problem several years ago. And when I came to very knowledgeable mechanic so he fixed it for me for free and he told me how to fix it by myself in future if problem will come back: Try to play with your 4Hi and 4HI LOCK buttons, pressing them one after another one to let your transfer case motor to switch mode of transfer case from one to another one. You should do it when your track is not moving( you can do it even during long red light waiting on intersections!) and you should do it at least 20-30 times pressing buttons back and forth letting TC Motor to change mode for transmission. That mechanic-guy told me that it's a "Rule of 30 switches". When you do this procedure your TC motor start to work again and clean some residue this way, that could stay on the rotor and electric brushes of TC Motor after it didn't work for long period of time. So when your TC Motor do it for about 20-30 time, changing modes from 4HI to 4HI LOCK and back it could fix your problem! But be sure that your truck is STATIC and it's not moving during that procedure!
After one or two years this problem with DIC message:"Service 4WD"came back and I fixed it right away with this procedure!
I hope that it could help you for free! By the way, that mechanic guy was former GM specialist and employee!
Try it! And good luck!