I used the 3000MCD unit with a 100ohm resistor...it kills the sunroof control!<p>I'm guessing this doesn't happen with your 270ohm resistor, cuz you don't mention it...but it looks like that LED is drawing enough voltage to keep the sunroof control from functioning.<p>It took me 15 minutes to figure out that I HAD wired everything as you specified...the trick to getting the sunroof control back is to close the circuits to the dome lights by pushing BOTH(!) of them to turn on the dome lights...then the sunroof control works again.<p>I like the intensity with the 100 ohm resistor & really don't want it dimmer, so I think I'll wire a switch in, if I can find a small grey or black switch that would not look too obtrusive up there.<p>Thinking out loud (correct me if wrong): I don't think grounding to the sunroof ground would have any effect? Only if that switch actually prevents the ground side from reaching ground until pressed (doesn't make sense, cuz stan's works...)<p>So...the warning is: If your sunroof dial control stops working, then it is likely you need a higher ohm resistor: you could put another one in series...remember series is R1+R2, parallel is 1/((1/R1)+(1/R2)).<p>Man...love the light....hate the fact that I freaked cuz I couldn't figger out why my sunroof stopped working! Blech...<p>steve...waiting for my Hella horns from Imparts!

Hey Steve, let me know how those horns turn out....the red ones, right?<p>I have been eyeing those two for about a month now.<p>Steve S.<br>97 2.8QM

I have also been eyeing those eardrum candy devices (at least for the honker).<p>Let me know too!<p>Kirk<br>(Thinkin' those big SUV's don't hear me so well over their FORD Mach stereos...)

Well, that's cool. Of course I never checked the sunroof - it's not really what we'd call warm outside (-5C yesterday, sunny CA). But I just ran to the car and my sunroof still works.<p>Correct me if I am wrong - I may be, I switched from EE to CS during sophomore year and that's a while ago, but the current drawn by our LED is 20mA either way. The resistor only divides the voltage supplied by the sunroof wire (4V) into whatever the LED can handle and into "garbage" which simply gets baked at the resistor. So say we are losing 2V at 20mA at the resistor. Totally, we are baking 20mA at 4V, i.e. 80mW. That can't kill the sunroof, unless of course I am missing something.<p>Also the trick you described to get the sunroof to work sounds sketchy. The only way to turn the LED off is to turn off ignition and open the door. <p>I would suggest that you check that you aren't touching GND somewhere with the LED or with the red wire that we tapped. That may explain things. Remember, always nicely isolate lose wires :-)<p>If this persists I may use a day of Xmas break to figure out a different way to power the LEDs. Let me know.<p>- Stan<br>

So I am still thinking about stevebrown's problem... It really can't be the LED. If 20mA of current throws the stuff upside down, something is wrong with the design. A light bulb would be a different story, but you have to be actually looking for a LED in order to find it.<p>Also, from what you write, that pressing the two buttons at the same did the trick - our LED is completely independent of the map lights, we just tap GND there and that won't go away if you press the switches. I suspect that you are touching GND somewhere with one of the other wires, or the LED is touching the roof (which is GND as well). That will of course immediately draw the power away from the sunroof control.<p>The resistor size doesn't really matter: here the resistor is a voltage splitter. The same current goes thru the LED as thru the resistor; it's just a question what fraction of the 4V gets fried at the LED and what at the resistor. The resistor will not influence the total current we draw. <p>Make sure you are not touching ground where you should not, that the sunroof plug is properly attached, and that the resistor is of sufficient minimal value based on the provided formula.<p>Good luck, let me know how it goes.<br>- Stan<br><ul><li><a href="http://rescomp.stanford.edu/~stanj/Audi/Dome/index.html">The by now famous red dome light instructions</a></li></ul>

I wrapped all the wires in electrical tape & they definitely aren't touching anything...<p>...it still makes no sense to me! <p>Pushing the two switches to close those circuits makes the sunroof dial switch work again, while the LED remains lit the entire time. <p>I desoldered the ground wire for the LED & verified the behavior by hooking everything up (except said ground wire). The dial switch works normally & the LED is out. When I touch the ground wire to the solder point for the button switch ground, the LED lights & the dial switch dies.<p>Frustrating...<p>steve

Steve,<p>you never post your email address so I can't reply to you. I think it's better to take this offline.<p>I'd suggest you go with the same LED as I have (2000mcd, part # on my page) and use the minimum resistor of 80 ohm if you like it bright. That still will work - at least in my car it did.<p>- Stan<br>

I emailed Stan with the fix for the problem... it's not hard..<p>Rich Quinlan<ul><li><a href="http://home.att.net/~richquinlan">Quinland</a></li></ul>

I still think your favorite tool is the hammer though.... :-)<p>Steve S.<br>97 2.8QM