GMC 1993 Suburban Owner's Manual page 143

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.
Don't keep driving if the oil pressure is low. If you do, your engine
can become so hot that
it
catches on fire. You or others could be
burned. Check your oil as soon as possible and have your vehicle
K2336
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 in either warning zone indicate a possible problem in the electrical
system.
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