In my experience it looks like triggering the light is justas easyas hitting the box with the vacuum. The lady I bought the 2.8 from aid it heppend to hr twice to pick up the car from the cleaner and having the airbag light on.
That's why I was recommanding cleaning the connectors and securing the box behind the seat cover as opposed to using the BMW connector...
---------------------------------
1998 Z3 1.9 - few modifications here and there
1999 Z3 2.8 - individual edition (British Traditional)
2003 Z4 2.5i