Airbag dashboard light on - random and with no apparent reason

Hi, I have a 2002 Dodge Grand Caravan that was professionally modified with a lowered
floor and other equipment for wheelchair accessibility. I arranged to sell it today and,
wouldn't you know it, at 6 p.m. on Friday night the SRS light on the dashboard was on
when the buyer returned from a test drive. It was raining, and I only offer that because
the last time I had a similar issue, it was also raining and some re-wiring was done in
the van during that service visit. Also the buyer is a very short woman who moved the
driver seat up very far forward from when I normally keep it -- don't know if that has
anything to do with this problem but it is not how the van is usually set. Six years ago I
had a very similar issue and I think it was seat belt related rather than actually being a
problem with the airbag. I understand that a regular code scanner wouldn't pick up
anything because this isn't related to the power train or other things most scanners
read. I'm no mechanic and I don't have 2 weeks to wait for the local dealer to fit us in for
an appointment -- can anyone recommend the type of scanner I need to ask mechanic
shops if they have? I've called around to a couple of local auto part stores and service
shops but so far no one has been able to help or guidance. All of the mechanic shops
are closed for the night and usually Saturdays are pretty packed. The 2 closest Dodge
dealers have no slots until about the 12th -- long after the sale of the car should be
finished. Any ideas?