can you shift this thing ON THE FLY?
Never had a vehicle with this type of multi-purpose driving selections. The wife drives it, and snow will be here soon, I did read the manual and it says to go to neutral and put in selected gear moving at a slow pace 1 to 2 MPH . my questions is can you go from normal 2wd to 4AWD driving down the road doing the speed limit, or does she have to pull over and put it in neutral to select 4AWD or 4HI? I know not to go to 4LO doing that. Just do not want her to damage the drivetrain.
Thanks in advance for any help. Mike

Yes, you can go in any direction between 2 high, auto 4WD, and 4 high at whatever speed.

From your manual:

OK I guess I read it wrong, just seems to me it would hurt something shifting on the FLY, Thanks for the clarification I will tell her to do it this way, and never go into 4lo without me there or at least call me first, but hell she is never offroad anyway. How bullet proof is this system? Like I said I have never had or seen any system like this, to tell you the truth never even knew it existed. THANKS
Thanks for the answer

Moved from the "Buick" forum to the "GMC/Chevrolet Truck/SUV" forum.

It'* pretty bulletproof. Mostly the problems with these are electronics that aren't in the transfer case itself.

Auto 4WD locks in the front axle without locking in power to the front wheels from the transfer case. Then it monitors for rear wheelspin. When it detects enough wheelspin in the rear, it engages clutches in the transfer case that send power to the front wheels as needed. It can be left on all the time, but will sacrifice some fuel economy as it turns the front differential, pinion, and drive shaft all the time. My suggestion: If the weather outside if frightful, put it in Auto 4WD. When something slippery happens it will take pretty good care of it . . . and no risk of driveline damage by leaving it engaged (as would happen in 4 high).