Chevrolet Repair: Front axle/transfer case, cv joints, rear wheels

Question
Vehicle: 2009 Tahoe LT, 5.3L FlexFuel V8, 4WD 65,000 mi

Do the front axles/cv joints rotate independently of the front wheels when the vehicle is in 2wd?  I noticed a slight 'buzz' in the steering wheel the other day while driving so I had my wife let the truck roll foward and backward slowly while I watched the axles.  They were rotating with the front wheels.  The 4wd indicator (on a dial) shows that it is in 2wd.  I took it to the local dealer today and was told that this is normal that the axles rotate regardless of whether in 2wd or 4wd.  I was skeptical so I am trying to find a definitive answer.

Thanks

Answer
HI ANDY,,YES ANDY THE FRONT AXLES WILL MOVE WHEN THE TRUCK ROLLS,HOWEVER IF YOU WERE TO JACK ALL FOUR WHEELS UP AND PUT IT IN DRIVE IN 2 WHEEL DRIVE THE REAR WHEELS SHOULD BE THE ONLY ONES MOVING UNTILL YOU LOCK IT IN 4WD. YOU SEE THE AXLES WILL LOCK TOGETHER IN THE AXLE HOUSING BY A COUPLER WHEN IT IS COMMANDED TO DO SO WHEN YOU LOCK IT IN 4WD. BUT THE FRONT AXLES WILL MOVE FREELY WHILE DRIVING, BUT THEY ARE NOT LOCKED IN. THEY ARE JUST ROLLING ALONG FOR THE RIDE. [[YOU ARE THINKING ABOUT THE OLDER TRUCKS WITH LOCK OUT HUBS..THING OF THE PAST,EVERYONE GOT LAZY.]] THIS IS NORMAL UNLESS YOU HAVE ALL TIME 4 WHEEL DRIVE,WHICH I NKOW YOU DO NOT....I HOPE THIS HELPS YOU,,,TOM