1997 GMC Jimmy Owner's Manual - Page 135

Voltmeter Gage When your engine is not running. but the ignition is on (in the RUN position). this gage shows y o u r battery's stateof charge i n DC volts. VOLTS Readings i n the low warning mne m a y occur when a large number of electrical accessories are operatingin the vehicle and the engine is left at an idle for an extended period. This condition is normal since the charging system is not able to provide full power at engine idle.As engine speeds are increased,this condition should correct itself as higher engine speeds allow the charging system to create maximum power. You can only drive f o r a short time with the reading in either warning zone. I f you must drive, turn off a l l unnecessary accessories. 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 i n the electrical system. Have the vehicle serviced as soon as possible. 2-74