2008 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 223

Charging System Light This light will come on briefly when you turn on the ignition key, but the engine is not running, as a check to show you it is working. Voltmeter Gage Your vehicle may have a voltmeter gage. It should go out once the engine is running. If it stays on, or comes on while driving, there could be a problem with the charging system. A charging system Driver Information Center (DIC) message may also appear. See DIC Warnings and Messages on page 3-66 for more information. This light could indicate that there are problems with a generator drive belt, or that there is an electrical problem. Have it checked right away. If you must drive a short distance with the light on, be certain to turn off all the accessories, such as the radio and air conditioner. When the ignition is on, this gage indicates the battery voltage. When the engine is running, this gage shows the condition of the charging system. The gage may transition from a higher to lower or a lower to higher reading, this is normal. If the vehicle is operating outside the normal operating range, the charging system light will come on. See Charging System Light on page 3-45 for more information. The voltmeter gage may also read lower when in fuel economy mode. This is normal. 3-45