GMC 2007 Envoy Denali Owner's Manual page 125

If the knob is turned to Four Wheel-High, Auto
Four-Wheel Drive, or Two-Wheel High when your
vehicle is in gear and/or moving, the Four-Wheel
High, Auto Four-Wheel Drive, or Two-Wheel
High indicator light will flash for 30 seconds. It will
not complete the shift unless your vehicle is
moving less than 2 mph (3.2 km/h) with the
transmission in NEUTRAL (N).
Shifting into NEUTRAL
Before shifting the transfer case to NEUTRAL, first
make sure the vehicle is parked so that it will
not roll.
1. Set the parking brake.
2. Start the vehicle.
3. Put the transmission in NEUTRAL (N).
4. Shift the transfer case to Two-Wheel High.
5. Turn the transfer case knob all of the way past
Four-Wheel Low and hold it there for a
minimum of 10 seconds. The neutral indicator
light will come on.
6. With the engine running, shift the transmission
to REVERSE (R) for one second, then shift the
transmission to DRIVE (D) for one second, to
ensure that the transfer case is in NEUTRAL.
7. Turn the engine off, by turning the key to
ACCESSORY.
8. Place the transmission shift lever in PARK (P).
9. Turn the ignition to LOCK.
Shifting Out of NEUTRAL
To shift the transfer case out of NEUTRAL, do the
following:
1. Set the parking brake and apply the regular
brake pedal.
2. Turn the ignition to RUN with the engine off.
3. Put the transmission in NEUTRAL (N).
4. Turn the transfer case knob to the desired
position (Two-Wheel High, Four-Wheel
High, or Auto Four-Wheel Drive).
5. After the transfer case has shifted out of
NEUTRAL, the indicator light will go out.
6. Release the parking brake.
7. Start the engine and shift the transmission to
the desired position.
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