GMC 2011 Sierra Owner's Manual page 348

If the vehicle has Four-Wheel
Drive, you can send the engine's
driving power to all four wheels
for extra traction. To get the most
satisfaction out of Four-Wheel
Drive, you must be familiar with its
operation. Read the following before
using Four-Wheel Drive. See the
appropriate text for the transfer
case in the vehicle.
While driving on clean dry pavement
and during tight turns, you may
experience vibration in the steering
system.
If the vehicle has StabiliTrak
shifting into Four-Wheel Drive
Low will turn Traction Control and
StabiliTrak off. See
.
The front axle engages and
disengages automatically when you
shift the transfer case. Some delay
for the axle to engage or disengage
is normal.
®
,
The transfer case shift lever is on
the floor to the right of the driver.
Use this lever to shift into and out
of Four-Wheel Drive.