GMC 2011 Sierra Owner's Manual page 356

To shift the transfer case to
N (Neutral) do the following:
1. Make sure the vehicle is parked
so that it will not roll.
2. Set the parking brake and
press and hold the regular brake
pedal. See
for more information.
3. Start the vehicle or turn the
ignition to ON/RUN.
4. Shift the transmission to
N (Neutral).
5. Shift the transfer case to
Two-Wheel Drive High.
6. Turn the transfer case dial
clockwise to N (Neutral) until
it stops and hold it there until
the Neutral light starts blinking.
This will take at least
10 seconds. Then slowly release
the dial to the four low position.
The N (Neutral) light will come
on when the transfer case shift
to N (Neutral) is complete.
7. If the engine is running, verify
that the transfer case is in
N (Neutral) by shifting the
transmission to R (Reverse)
for one second, then shift the
transmission to D (Drive) for
one second.
8. Turn the ignition to
ACC/ACCESSORY, which
will turn the engine off.
9. Place the transmission shift
lever in P (Park).
10. Release the parking brake prior
to moving the vehicle.
11. Turn the ignition to LOCK/OFF.
To shift the transfer case out of
N (Neutral) do the following:
1. Set the parking brake and apply
the regular brake pedal.
2. Turn the ignition to ON/RUN
with the engine off, and shift
the transmission to N (Neutral).
3. Turn the transfer case dial to
Two-Wheel Drive High.
After the transfer case has
shifted out of N (Neutral), the
N (Neutral) light will go out.
4. Release the parking brake prior
to moving the vehicle.