2004 Chevrolet Avalanche Owner's Manual - Page 196
2004 Chevrolet Avalanche Manual
Page 196 highlights
This light will come on when you start your vehicle, and it will flash for a few seconds. Then the light should go out. This means the system is ready. {CAUTION: If the air bag readiness light stays on after you start your vehicle, it means the air bag system may not be working properly. The air bags in your vehicle may not inflate in a crash, or they could even inflate without a crash. To help avoid injury to yourself or others, have your vehicle serviced right away if the air bag readiness light stays on after you start your vehicle. The air bag readiness light should flash for a few seconds when you turn the ignition key to RUN. If the light doesn't come on then, have it fixed so it will be ready to warn you if there is a problem. If the air bag readiness light stays on after you start the vehicle or comes on when you are driving, your air bag system may not work properly. Have your vehicle serviced right away. 3-34