Service AirBag light-What's this all about?

2002 Envoy with 27,500 miles. Yesterday when my wife was driving the Envoy the air bag light came on and the display came on and it said "service the air bag" or something close to that. She told me about it when she came home so I took it for a test drive and sure enough the light and the display came on. When I was sitting in the driveway with the engine running,I was pushing the button on the steering wheel to see if the odometer(mileage)window would show up. You could not change it,only the service air bag display would be there. After a couple of minutes though the light went off and the mileage display came back on. I waited at least an hour and went out and started it and the air bag and display was on again. This time I let it running for 30 minutes to see if it would go off. It didn't. Turned the Envoy off and came out an hour later to try it again and the light did not come on and everything was normal. I looked in the owners manual and it say's there is no service that you can do for the air bag. Does anyone know what is going on with this? This is the first vehicle that has had this problem. What is there to "service" on the air bag? Thanks for your help! John

The service airbag light is to inform you that there is a fault in the airbag system.

With that light on, the air bags will not deploy in an accident. You need to bring it to your dealer to see what the problem is in the system. It should be under warranty still and is probably something very simple to fix.

Hope this helps.