I have gotten a rapid warning chime on a couple of occasions when I get in the van. I am not finding what it is for but it goes off when I start the van.

I am slowly finding out what it isn't but can not find a list of what conditions cause a chime and which are fast and slow.

Those I am aware of are:
- low gas
- seat belt
- head lights
- keys in the ignition and door open

Others?