GMC 2011 Sierra Owner's Manual page 341

could be injured. To be sure the
vehicle will not move, even when
you are on fairly level ground,
always set the parking brake and
move the shift lever to P (Park).
See
. If you are pulling a
trailer, see
If you have Four-Wheel Drive, the
vehicle will be free to roll
if the shift lever is in P (Park)
the transfer case is in Neutral.
So, be sure the transfer case is
in a drive gear, Two-Wheel Drive
High or Four-Wheel Drive High or
Four-Wheel Drive Low
Neutral. See
.
back up.
To rock the vehicle back and forth to
get out of snow, ice, or sand without
.
damaging the transmission, see
engine does not connect with the
wheels. To restart when you are
already moving, use N (Neutral)
even
only. Also, use N (Neutral) when
if
the vehicle is being towed.
not in
Use this gear to
.
In this position, the
Shifting into a drive gear while the
engine is running at high speed is
dangerous. Unless your foot is
firmly on the brake pedal, the
vehicle could move very rapidly.
You could lose control and hit
people or objects. Do not shift
into a drive gear while the engine
is running at high speed.