GMC 2013 Sierra Owner's Manual page 308

9-42 Driving and Operating
Shifting into Four-Wheel Drive
Low with the vehicle at a stop
may be more difficult. You may
be unable to complete the shift
to Four-Wheel Drive Low, and
the transfer case will end up in
N (Neutral). This is normal, and
is a function of the gear teeth
aligning in the transfer case.
When this happens, make sure
the engine is on, shift the
transmission momentarily to
D (Drive) and back to
N (Neutral), and then complete
the transfer case shift.
Shift the transfer case shift lever
in one continuous motion into
the Four-Wheel Drive Low
position.
When in Four-Wheel Drive Low
do not drive faster than
72 km/h (45 mph). This will
reduce wear and extend the life
of your transfer case.
Shifting In or Out of Neutral
1. With the vehicle running and the
engine at an idle, set the parking
brake.
2. Place the transmission into
N (Neutral).
Shift the transfer case in one
continuous motion into or out of the
N (Neutral) position.
I n f o r ma t i o n P r o v i d e d b y :
Electronic Transfer Case
The transfer case knob is located
next to the steering column.
Use the dial to shift into and out of
four-wheel drive.