GMC 1994 Yukon Owner's Manual page 133

A reading in the low pressure zone may be caused by a dangerously low oil
level or other problem causing low
oil pressure. Check your oil as soon as
possible.
A
CAUTION:
Don't keep driving if the oil pressure is low. If you do, your
engine can become so hot that it catches fire. You or others could
be burned. Check your oil as soon as possible and have your
vehicle serviced.
NOTICE:
Damage to your engine from neglected oil problems can be
costly and is not covered by your warranty.
Voltmeter
Standard Cluster Tachometer Cluster
When your engine is not running, but the ignition is on (in the RUN
Position), this gage shows your battery's state of charge in DC volts. When
the engine is running, the gage shows the condition of the charging system.
Readings between the low and high warning zones indicate the normal
operating range.
Readings i n either warning zone indicate a possible problem in the electrical
system.
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