I have an lly but I looked into the problem and I guess it is a pretty common problem but usually not a big deal. Take it in and they check for a B2725 code. My service notes say "R&R the dash FACIA and replace the dash switch". Usually if you get that error and the 4wd still works like normal then a bad switch is the problem.
i had a similiar issue a few years ago. It ended up being a bad switch and not the encoder motor. Much better since the switch is much less $$$ and a tool less repair that you can do yourself vs an encoder which can be a bit of a pain.
I did the encoder motor myself; it's just the sensor that goes bad, not the whole motor assy. I think the part was $85 from Merchant. It's not bad if you have the procedure (I've got it in Word somewhere) -- normal hand tools and about an hour and a half if you take it slow. The stealer will want to charge you $200 for a whole new motor assy., and then $200 in labor. Not necessary.
Lots of discussion on the switch vs. sensor in the Drivetrain forum, like I said originally.
I've seen several GM trucks with the push button 4WD go bad, I've replaced some, each time it was a Service 4WD, just a bad switch on the dash. Replaced them, no problems. It's an easy unplug and plug back in once you remove the dash face plate. My father in laws Service 4WD light came on, it was stuck in between 2wd and 4wd, could not drive it, had to have it towed. It was an actual electrical switch down on the differential. Chris
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