Hummer 2006 H2 - Manual (Page 316)

Press the height control button to raise the rear of the
vehicle.
A light in the button will begin to flash as the rear of the
vehicle rises. Once the extended height has been
reached (this may take up to a minute), the warning
light will stop flashing and will stay lit while the vehicle is
at the extended height.
To lower the vehicle to the normal ride height, press the
button again. The light in the button will flash as the
suspension lowers. When the light in the button stops
flashing and goes out, the suspension has reached
the normal ride height.
This feature will lower the vehicle to the normal height if
vehicle speed exceeds 40 mph (64 km/h).
You may also want to use this feature when ascending,
descending or cresting a steep hill as this can help
prevent the rear bumper from dragging on the base of
the hill or prevent the vehicle from grounding out
(high centering) on the crest of the hill.
Do not use this feature when towing a trailer.
Electronically Controlled Air
Suspension System
The electronically controlled air suspension, if equipped,
keeps the rear of your vehicle level as you load and
unload it. The system includes a compressor, two height
sensor and two air springs supporting the vehicle.
The engine must be running for the system to level the
vehicle after loading or unloading. The system will
suspend leveling if any of the doors are open. Once the
doors are closed, system leveling will continue.
You may hear the compressor running when you load
your vehicle, and periodically as the system adjusts
the vehicle to the standard ride height. You may
also hear the release of air similar to a hissing sound
during suspension operation. This is normal.
Load leveling will not function normally with the inflator
hose attached to the inflator outlet. Remove the
inflater hose from the outlet when it is not in use. See
Accessory Inflator on page 5-68.
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