On my 2000 Silverado z71 when mine did this...i took out the 4 wheel drive push button module took it all apart and noticed the solder joints were cracked on some of the connections....i resoldered all of them...... put it all back together and it works like new now.....give that a try instead of a new one at $300 bucks.
Jeff

 

is there a possibility it could be the actuator in the front diff?

 

Maybe, do you know how I can check it?
Thanks.

"On my 2000 Silverado z71 when mine did this...i took out the 4 wheel drive push button module took it all apart and noticed the solder joints were cracked on some of the connections....i resoldered all of them...... put it all back together and it works like new now.....give that a try instead of a new one at $300 bucks."
Jeff

I will try this also. Thanks.

 

When mine got hung in 4 wheel drive ...it started doing it kinda erraticly at first..... like i would press the buttons and sometimes it would shift from one mode to the next or just hang in one mode and some days it would work just fine....it got so bad where i would keep pressing holding more pressure on the button then it may or may not shift at all and just hang in the last mode selected....thats what prompted me to take the switch module apart to check the connections....and after the resolder job it worked like new.....wont hurt to try...I read others have this same issue.

Jeff

 

Have 99 Z71 with 215000 mi, started out saying service 4 wheel drive and would not come out of 4hi. Kept trying everything, only would come out by stopping and shutting the key off or disconnecting the battery and it would come out.

Finally it stopped working all together, replaced the front diff motor, still would not work even though old one was bad. Finally took the push button switch apart very carefully and cleaned all the contacts with alcohol, used a paper clip to push the rubber tit's back in the correct positions and all works as good as new..

These switches are similarly like a TV remote control inside with the rubber contacts so if you have ever had a TV remote apart you know what your looking at..

 

For what it's worth, the same thing happened to my '99. I finally got it out by sitting in the driveway and shifting back and forth from drive to reverse and cycling the 4wd buttons. It eventually went into 2HI after several tries.
Good luck.

 

Thanks guys,
I'll try these.

 

I am interested in what became of your 4 wheel drive issue. I have an '05 Suburban. And in the owner manual it doesn't show the picture of the buttons that I have. The top picture is the car with tire tracks behind it, the middle button is 4 tires with the front ones turned slightly and the bottom button is 4lo. Ever since I bought the truck it has been on the middle button. my husband thought that that meant 4 wheel drive, and perhaps why I was getting bad gas milage. So last night I got it into 4 lo. Then I couldn't get it out again...my husband got it back to the middle button being lit.
Can anyone tell me what these buttons are and what they mean.
Sorry, I am not dense or anything, but I have never had these issues before. thanks!

 

dawniey5, it sounds like your Suburban has Stabilitrak.

Here's what the manual says (it's page 2-33 if you have a manual, if not, check it out online).

All-Wheel Drive with Stabilitrak®
With this feature, engine power is sent to all four wheels all the time. This is like four-wheel drive, but there is no separate lever or switch to engage or disengage the front axle. It is fully automatic, and adjust itself as needed for road conditions. The transfer case buttons are located to the left of the instrument panel cluster. Use these buttons to shift into and out of four-wheel drive.

You can choose among three driving settings:

Top (Stabilitrak®): This button is used with the Stabilitrak® system and is also used to shift the transfer case into Neutral (N). For more information on using Stabilitrak® see Stabilitrak® System on page 4-12.

Middle (All-Wheel Drive): This setting delivers power to all four wheels as needed depending on road and driving conditions.

Bottom (4LO): This setting delivers extra torque. You may never need this setting. It sends maximum power to all four wheels. You might choose 4LO if you are driving off-road in deep sand, deep mud, deep snow and climbing or descending steep hills.

 

Flainn,
Yes, I believe it has stabilitrak, BUT it will not shift into the top button. No light comes on when I push it...manual isn't really good at explaining that.

On a side note, NOT HAPPY that when I contacted Chevy about getting a new GPS disk, I was told I would have to purchase it as I did not buy my truck from a Chevy dealer...my argument was that it should not matter, especially when I paid $17,000 for my truck!!!!!!! At this rate (and this is my 4th suburban) I am seriously thinking about going to a Ford Excursion soon.