Voltmeter Gage - GMC TopKick 2007 Owner's Manual

Voltmeter Gage

Readings in either warning zone indicate a
possible problem in the electrical system.
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When your engine is
running, the voltmeter
gage shows the
charging system
voltage.
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 at
an idle for an extended period. This condition
is normal since the charging system may not be
able to provide full power at engine idle. As engine
speeds are increased, this condition should
correct itself because higher engine speeds allow
the charging system to create maximum power.
You can only drive a short time on the battery.
Be sure to shut off the radio, the fan or any
unnecessary accessories and have the system
serviced.