Hummer 2007 H3 Owner's Manual page 114

Press and release the Four-Wheel High or
Four-Wheel-High Lock button. If your vehicle has
a manual transmission, the clutch pedal must
be pressed to the floor while you press the
Four-Wheel High or Four-Wheel-High Lock
button, or the shift will not be completed.
You must wait for the Four-Wheel High or
Four-Wheel-High Lock indicator light to stop
flashing and remain lit before shifting your
transmission into gear.
It is normal for your vehicle to have engagement
noise and bump when shifting between
Four-Wheel Low and Four-Wheel High ranges
or from NEUTRAL with the engine running.
If the Four-Wheel High or Four-Wheel-High Lock
button is pressed when your vehicle is in gear
and/or moving too fast, the Four-Wheel High
or Four-Wheel-High Lock indicator light will flash
for 15 seconds but will not complete the shift
unless your vehicle is moving less than 3 mph
(5 km/h) and the transmission is in NEUTRAL (N).
114
Shifting Into NEUTRAL
To shift the transfer case to NEUTRAL, do the
following:
1. Set the parking brake.
2. Start the vehicle by turning the ignition to
START.
3. Put the transmission in NEUTRAL (N).
If your vehicle has a manual transmission,
press and hold the clutch pedal down
while you perform Steps 5 through 9.
4. Shift the transfer case to Four-Wheel High.
CAUTION:
{
Shifting an all-wheel-drive vehicle's
transfer case into NEUTRAL can cause
your vehicle to roll even if the automatic
transmission is in PARK (P) or the manual
transmission is in any gear. You or others
could be injured. Make sure the parking
brake is firmly set before you shift the
transfer case to NEUTRAL.