Hummer 2008 H2 - Manual (Page 187)

Charging System Light
This light will come on
briefly when you turn
on the ignition, but
the engine is not running,
as a check to show
you it is working.
It should go out once the engine is running. If it stays
on, or comes on while you are driving, you may have
a problem with the charging system. A charging system
Driver Information Center (DIC) message may also
appear. See DIC Warnings and Messages on page 3-56
for more information. This light could indicate that
you have problems with a generator drive belt, or
another electrical problem. Have it checked right away.
If you must drive a short distance with the light on,
be certain to turn off all your accessories, such as
the radio and air conditioner.
Voltmeter Gage
When your engine is
not running, but the
ignition is on, this gage
shows the battery’s
state of charge in
DC volts.
When the engine is running, the gage shows the
condition of the charging system. The charging system
regulates voltage based on the state of the battery
for improved fuel economy and battery life. The gage
may transition from a higher to lower or a lower to
higher reading, this is normal. Readings between
the low and high warning zones indicate the normal
operating range. The gage may also read low during
the fuel economy mode, this is normal.
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