GMC 2011 Sierra Owner's Manual page 350

If the vehicle has StabiliTrak
shifting into Four-Wheel Drive
Low will turn Traction Control and
StabiliTrak off. See
.
A parking brake symbol is located
next to the N (Neutral) symbol as a
reminder to set the parking brake
before shifting the transfer case into
N (Neutral).
®
,
Shifting the transfer case to
N (Neutral) can cause the vehicle
to roll even if the transmission
is in P (Park). You or someone
else could be seriously injured.
Be sure to set the parking brake
before placing the transfer case
in N (Neutral). See
only when the vehicle needs to be
towed. See
.
Shift to this setting
or
.
setting is used for driving in most
street and highway situations.
The front axle is not engaged in
two-wheel drive. This setting also
provides the best fuel economy.
this setting when you need extra
traction, such as on snowy or icy
roads or in most off-road situations.
This setting also engages the front
axle to help drive your vehicle.
This is the best setting to use
when plowing snow.
You can shift from Two-Wheel Drive
High to Four-Wheel Drive High
or Four-Wheel Drive High to
Two-Wheel Drive High while the
vehicle is moving. In extremely
cold weather, it may be necessary
to stop or slow the vehicle to shift
into Four-Wheel Drive High.
This
Use