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For visibility I like to drive my old cars with the parking and sometimes the headlights on, even during the day. The problem is forgetting to turn the lights off and running down the battery. I borrowed this idea from the UK E-type site but many other old car forums have a similar solution. The principle is to insert a light/alarm into the parking light circuit for power and use the door jam switches as the ground. Below is a short Youtube video of the circuit in operation. First I turn on the parking lights, remove the keys, and open the door. The alarm goes off when I shut the door (or turn off the lights).


The alarm is a 12 volt LED/beeper from amazon. They come in a wide variety of colors and sizes and are cheap. Fuses 4 and 5 are the L&R parking light circuits. They are internally connected and there is an unused spade on terminal 5. I used this for the power source to the beeper. This comes from the unfused side of the circuit so I added a 3 amp fuse. I mounted the beeper on a small bracket beside the heater controls under the dash but you could put it in many locations. Under the right side of the dash the two ground leads from the door switches connect to a single black wire going up to the interior light in the mirror. You can see this area in the bottom right photo below. This is where the ground from the beeper connects. I made a short pigtail to connect the two door grounds with the one from the beeper and then all 3 join the single lead to the light. The final item needed is a diode to prevent back flow of current through the beeper. Without it the beeper will sometimes sound when the doors open even with the lights off, or the interior light may dim and not go out with the door closed. I used a 1N4007 diode soldered to the ground lead and oriented so current can only flow from the beeper to the ground. In the picture below I show the diode before and then covered with heat shrink in the pigtail ground. A softer chime would be nice but this will get your attention.



Headlight warning Buzzer.gif
 
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