2002 GMC Sonoma Owner's Manual - Page 142

Charging System Indicator Light CAUTION: If the air bag readiness light ever comes on when you have turned off the air bag, it means that something may be wrong with the air bag system. The right front passenger's air bag could inflate even though the switch is off. If this ever happens, don't let anyone whom the national government has identified as a member of a passenger air bag risk group sit in the right front passenger's position (for example, don't secure a rear-facing child restraint in your vehicle) until you have your vehicle serviced. The charging system light will come on briefly when you turn on the ignition, but the engine is not running, as a check to show you it is working. It should go out once the engine is running. If it stays on, or comes on while you are driving, you may have a problem with the charging system. It could indicate that you have problems with a generator drive belt, or another electrical problem. Have it checked right away. Driving while this light is on could drain your battery. If you must drive a short distance with the light on, be certain to turn off all your accessories, such as the radio and air conditioner. 2-72