GMC 2007 Yukon XL Owner's Manual page 128

It is not recommended that you drive with the
liftgate open, however, if you must drive with the
liftgate open, the power liftgate should be switched
to manual liftgate operation — the overhead
console switch set to the "Disable" position.
Both the liftglass and liftgate have an electric latch.
If the battery is disconnected or has low voltage,
the liftglass and liftgate will not open. The
liftglass and liftgate will resume operation when
the battery is reconnected and charged.
If the battery is properly connected and has
adequate voltage, and the liftgate or liftglass still
will not function, your vehicle should be taken to a
dealership for service.
CAUTION:
{
It can be dangerous to drive with the
liftglass or liftgate open because carbon
monoxide (CO) gas can come into your
vehicle. You cannot see or smell CO.
It can cause unconsciousness and even
death.
128
CAUTION: (Continued)
CAUTION: (Continued)
If you must drive with the liftglass or
liftgate open, or if electrical wiring or
other cable connections must pass
through the seal between the body and
the liftglass or liftgate:
•
Make sure all other windows are shut.
•
Turn the fan on your heating or
cooling system to its highest speed
with the recirculation mode off. That
will force outside air into your vehicle.
See Climate Control System on
page 210 or Dual Automatic Climate
Control System on page 213.
•
If you have air outlets on or under the
instrument panel, open them all
the way.
•
If your vehicle has a power liftgate,
disable the power liftgate function.
See Engine Exhaust on page 155.