GMC 2013 Sierra Denali Owner's Manual page 266

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 knob is located
next to the steering column.
Use the dial to shift into and out of
Four-Wheel Drive.