Hummer 2005 H2 - Manual (Page 110)

Shifting into 4LO Lock
To shift into 4LO Lock, the ignition must be in RUN and
the vehicle must be stopped or moving less than
2 mph (3.2 km/h) with the transmission in NEUTRAL (N).
The preferred method for shifting into 4LO is to have
your vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Press
and release the 4LO Lock button. You must wait for
the 4LO Lock indicator light to stop flashing and remain
lit before shifting your transmission in gear.
Notice: Shifting the transmission into gear before
the indicator light stops flashing could cause
damage to the transfer case. Always wait until the
indicator light stops flashing before putting the
transmission back in gear.
It is normal for your vehicle to have engagement noise
and bump when shifting between 4LO and 4HI
ranges or from NEUTRAL with the engine running.
If the 4LO Lock button is pressed when your vehicle is in
gear and/or moving, the 4LO Lock indicator light will flash
for 15 seconds and not complete the shift unless your
vehicle is moving less than 2 mph (3.2 km/h) and the
transmission is in NEUTRAL (N). After 15 seconds the
transfer case will return to the setting last chosen.
Shifting Out of 4LO Lock
To shift from 4LO Lock to 4HI or 4HI Lock, your vehicle
must be stopped or moving less than 2 mph (3.2 km/h)
with the transmission in NEUTRAL (N) and the ignition in
RUN. The preferred method for shifting out of 4LO
Lock is to have your vehicle moving 1 to 2 mph
(1.6 to 3.2 km/h). Press and release the 4HI or 4HI Lock
button. You must wait for the 4HI or 4HI 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 4LO and 4HI
ranges or from NEUTRAL with the engine running.
If the 4HI or 4HI Lock button is pressed when your
vehicle is in gear and/or moving, the 4HI or 4HI Lock
indicator light will flash for 15 seconds but will not
complete the shift unless your vehicle is moving less
than 2 mph (3.2 km/h) and the transmission is in
NEUTRAL (N).
Notice: Shifting the transmission into gear before
the indicator light stops flashing could cause
damage to the transfer case. Always wait until the
indicator light stops flashing before putting the
transmission back in gear.
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