On Mon, 2008-06-09 at 13:09 +0100, Alan B. Pearce wrote: > I seem to recall the project could detect something like 10-50mV drop in > voltage due to the draw from the lamp, and used a 555 timer as the detector, > but I may well be wrong on the latter bit. A wrinkle with this idea is these days the door switches no longer go to the lights. Instead stuff like this is handled by the "body control module". Why this is important is due to various features, a "light on" doesn't necessarily mean door open, and a "light off" doesn't mean doors closed. For example, my Toyota Matrix turns it's interior lights on when the "unlock" button is pressed on the keyfob. If you don't physically open the door within 30 seconds the doors lock and the light turns off. On the other side, if you open and door the light turns on, but if you leave the door open longer then a certain amount of time the light turns off. Opening any other door does not turn the light back on (I think), yet closing the door does!?? Until you put your key in the ignition, then the light turns off, or you hit the lock button. TTYL -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist