GMC 2007 Acadia - Manual (Page 221)

Voltmeter Gage
When the engine is
not running, but the
ignition is turned to ON,
this gage shows the
battery’s state of charge
in DC volts.
When the engine is running, this gage shows the
condition of the charging system. The vehicle’s
charging system regulates voltage based on
the state of charge of the battery. The voltmeter
may fluctuate. This is normal. Readings between
the low and high warning zones indicate the
normal operating range.
Readings in the low warning zone may occur
when a large number of electrical accessories
are operating in the vehicle and the engine is
left idling for an extended period.
If there is a problem with the battery charging
system, a SERVICE BATTERY CHARGING
SYSTEM message will appear in the Driver
Information Center (DIC) and/or the charging
system light will come on. See DIC Warnings and
Messages on page 244 and Charging System
Light on page 220 for more information.
However, readings in either warning zone may
indicate a possible problem in the electrical
system. Have the vehicle serviced as soon
as possible.
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