HeadLight Buzzer
Let's you know when you leave your lights on...

 
This schematic is for systems that the door switch switches ground for the interior lights (GMs) Lightsdsgnd1.jpg (84701 bytes)
 
This schematic is for systems that the door switch switches +12 volts for the interior lights.
Thanks to John Harcinske for this info....graphics, idea....all of it.  Another member of the MustangSteve Message Board