Photodiode Controlling Led Switches On Updated Dome Light Console In 850S (Bad Idea?)

[Bah]

So, anyone who has owned an 850, has more then likely had their overhead dome light console break at some point. All of mine have broken eventually, either the switches break, or the covers shatter or something happens...the x70 versions seem to last longer, but that's aside the point.

The X70 versions have the 3 buttons with LED back-lighting. Of course, there is the mod of using pin 8 and running a wire from this pin to the headlight switch, or really anywhere that does 12V instrument lighting (dash switches etc...). That's my understanding, and most people run the wire and hide it up under the headliner or stuff it and run it down the side.

That's easy enough, you just need an old harness, take the pin with a remaining slice of wire, and put it in pin 8, and add wire and mate it to your destination. Since the 850's aren't prewired for this, getting the wire where you want it is what turns me off. I don't plan on dropping the headliner anytime soon, and i don't know how easy it is to find an ignition wire source up in the sunroof.

So, the end result is there is no ignition wire you can use readily in the dome light harness. Poo.

I had an old broken console i just wanted to play with, and had a 9V nearby and just wanted to see what it looked like. Cool stuff. Did a quick check, was using ~7.5mA at 9V, so i'll check the draw at 12V but i imagine its not much more.

How about a solar diode/solar transistor? If its light outside, the lights will be off. Regardless of the car being on or anything else. If its dark outside, lights on, Regardless if the car is off or on.

Problems i see:

1. constant current draw. even if its 10mA, do you really want the extra draw on the battery? Not gonna kill the battery overnight or even in a month probably, since the car itself uses ~40mA for the alarm and everything? And if it only turns on at night, car location could affect this greatly. But assume you park your car in a dark garage all the time. Even if the car is in direct sunlight, there will be some draw i believe, but i hate analog and i slept through my amplifier design class. woops. it would be probably closer to ~1mA, but this is based on design.

2. If someone breaks into your car, they can now see where the dome lights are that much easier. Woops.

Advantages:

1. If you sit in your car with the lights off, and need to turn them on, they will be there for you to see. I never have had the problem of not knowing where the dome light switches are, hence why this is just for giggles, but i guess some people have and do. Even if you leave your car unlocked and have to close your door, you'll know where the switches are with no key in the ignition. Woah keanu reeves!

2. No wires hanging above your headliner, which has never been a problem for anyone before. But hey, wheres the fun in that.

Thoughts?

Keep in mind this mod would cost ~$3 tops, unless photodiodes are expensive. no need to get crazy and mill something etc, i'm thinking along the lines of 5-6 components max.

[Bah]

And i posted in the wrong forum...derp. Can i get this moved to cosmetic and detailing please?

[crazykn]

There is a ignition power source on the roof if you have a sunroof. I believe its the blue thick wire on the sunroof motor. This delivers the power for the sunroof, but its is not swtiched by the switch on the dash, thats done via a different wire.

I've had to use this wire to power my electrochromic mirror everytime I turn on the car and it works great.

[Serge]

You do not need to drop the headliner to run the extra wire. Peel back the A-pillar cover, unbolt the sun visor and remove the clip, then with the sunroof controls off, you have the original harness. Grab a pin from junk yard harness (use a thick needle or a thin screw driver to get the pin out), add it to the harness in your car (pin 8? I forget). Then tape it to the rest of the wires from that harness, tuck the excess wire behind the headliner (there is a tiny gap between the windshield and headliner, with the visor and clip off it will sag a bit). Feed it through to the A-pillar, run that down (behind the clips), fish it through to the dash by the nearest switch and connect it to a pink wire.

Easiest, cleanest, and most stock solution.