The airbag light shoud also set a code. The code can be obtained by a service tech. Or you can purchase an inexpensive code reader (OBD II) from an automotive store (Pep boys, Autozone, etc) The light could be caused by a fault in the airbag circuitry, crash sensors, the airbags themselves, or the seat belt circuitry or latches. The code will set you in the right direction.
Chris
February 2009