Hummer 2003 H2 Owner's Manual page 97

Liftgate
CAUTION:
It can be dangerous to drive with the liftgate open
because carbon monoxide (CO) gas can come into
your vehicle. You can't see or smell CO. It can
cause unconsciousness and even death.
If you must drive with the liftgate open or if
electrical wiring or other cable connections
must pass through the seal between the body
and the liftgate:
D
Make sure all other windows are shut.
D
Turn the fan on your heating or cooling
system to its highest speed and select the
control setting that will force outside air
into your vehicle. See "Comfort Controls"
in the Index.
D
If you have air outlets on or under the
instrument panel, open them all the way.
See "Engine Exhaust" in the Index.
To unlock the liftgate, use the unlock button on any
of the power door lock switches or the keyless entry
transmitter.
To open the liftgate, pull the handle located in the
center of the door.
Lock the liftgate by using the lock button on any
of the power door lock lock switches or the keyless
entry transmitter.
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