Airbag light on, is this a common problem?

[ozbmw]

1997 740iL (~140K miles) All of a sudden the airbag light turned. Is this a common problem? What makes it turn on? I didn't change/fix anything in the car before this turned on.
I took the car to a shop, and they discovered a bigger problem. The computer doesn't communicate with their scanner. There are two places where they can plug in the scanner. One inside the car which works fine, but it is limited and doesn't show all the problems. The other that is under the hood doesn't respond to the scanner. Any idea why???

I would love to hear your suggestions/answers/comments.
BTW, sorry for posting questions regarding a 7-series bimmer in the 5-series section. I am just used to this area and can't wait to fix this car, sell it and get back to a 5er...

[Dirty_Tool]

The airbag lamp will be turned on if there is a failure of any component in the airbag system. Some common failures are: seat belt tensioners, seat occupancy mat, and contact ring in the steering wheel. If the repair shop's tester will not communicate with the car using the 20-pin under-hood diag connector then it may be a fault in their tester. Which are they using? Is it a factory GT1 tester, or is it an aftermarket scanner such as for example the snap-on mt2500 scanner? If the problem is not the tester then sometimes a module will fail and pull the diagnostic bus line down (low voltage) and cause no modules on the Bus to communicate with any scanner. The only remedy is to start disconnecting modules 1 by until communication is resumed. Hopefully this isnt the case. My recommendation is to take the car to the dealer and see if their tester will communicate, if not then they are the best to diagnose the lack of communication problem anyway.
Good Luck,
DT