Air Bag dashlight

[DOC-K]

A friend, (non message board type) has a problem his dash light has been on for a l o n g time....(2000 BMW Z 3 M)
I remember from my E 30 day that there was often a problem with the seat belt/air bag electronics..
He had the car to a dealer, and an indie, and they told him that it might cost up to $2000 ..
What is the LOGICAL place to start checking components?
TIA

[calster]

I would check the connectors under the seat and seat sensor.

[uturn]

Check if the seat belt pyrotechnic charge hasn't already fired. The boot on the receptacle is usually straight, if it's buckled like an accordion then its been deployed. FYI- ~$240 for a new one.