1998 GMC Safari Owner's Manual - Page 143

Charging System Indicator Light 4 The charging system light will come on briefly when you turn the ignition on, but the engine is not running, as a check to show you the light is working. Voltmeter When your engineis not running, but the ignition is on (in the RUN position), the gage shows your battery's state of charge in DC volts. --+I Then it should go out once the engineis running. If it stays on,or comes on while you driving, you may are have a problem with theelectrical charging system.It could indicate that you havea loose accessory drive belt, or anotherelectrical problem. Have it checked right away. Driving while this light is on could drain your battery. If you must drive short distance with the light on, a be certain to turn off all your accessories, such as the radio and heatedair conditioner. . When the ignitionis 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 the low warning zone may occur when a large number of electrical accessories operating in are the vehicle and the engine left at an idle for an is extended period.This condition is normal since the charging systemis not able to providefull power at engine idle.As engine speedsare increased, this condition should correct itself as higher engine speeds allow the charging system create maximum power. to 2-59