my wife keeps asking for the same thing to be done in the bus! her honda
has one, and i gotta say it's pretty nice. I think selectively placed
relay off of the light swtich and ignition key switch thing would be the
trikc. But i don't htink it's as trivial as this. I am thinking some
digital logic, like a ttl gate.

put cascadeded  "AND" gate in there, like this i suppose:
-if lights are on
AND
-key is in the ignition
AND door is open
equals annoying chime.
else no chime

all of the necessary pick-up wires are there (the door open, key in
ignition and light on), but you';d need to slap a resistor in it to make
12v into 1v (or maybe they are 15V ttl chips?)....

matthew

Matthew Pollard          "Racing with the wind and flirting with death
Dept. Of Chemistry        So have a cup of coffee and catch your breath"
University of Idaho
www.uidaho.edu/~poll7356