Hey,
I have a 98 blazer with the pushbutton 4 wheel drive. Every now and then (once every couple of months) my truck seems to automatically put itself between 2 and 4 wheel drive. Usually I can back it up a 100 or so feet and it would pop back into 2 wheel drive. This time it didnt work. I dont know if its noteworthy or not but I tried putting it into neutral and hitting the 4-Hi switch and I heard a noise that resembled a solenoid clicking but it wouldnt go into 4.

Anyone have any tips on how to get it back into 2 wheel drive? Any idea on how to fix it permanently?

 

Also may be noteworthy: Once while backing up I floored it and the front tires spun so it sounds like its stuck in 4 wheel drive.

 

yup, if you take the battery and tray out you'll see the 4by actuator and cable, there is a how-to in the diy section to do the cable mod.

 

The other possible thing is your vacuum switch on your transfer case may not be venting the vacuum it is getting, locking the front axle in. This happened to me at 70 mph down a highway and these switches are notorious for going bad.