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Old 09-26-2012, 06:49 PM   #29
Registered User
Join Date: Aug 2012
Location: Tucson
Posts: 138
My Ride: 2000 323i
I'm not sure what a ugdo is. But as long as it provides a switched and constant power source then you will be able to tap all your wires there. If you use the relay, then you will have either choice of how you wire your relay. So I will show you how to wire it up with a constant 12v, a switched 12v, and constant ground. Here is a pic of the type of relay you can and can't use for this application. Since you want the led to turn on when the car is off, and turn off when the car is on, you must use a SPDT, not a SPST relay.

You can mount this little guy up in the headliner by the sunroof switch. I'm not sure if you have all of the proper signals up in the headliner so you will have to test with a voltmeter or probe.The sunroof switch or dome lights should have 12v constant,switched and ground, but I'm not positive. So what you will need is a constant 12v (this wire has 12v + regardless of key position), a 12v + switched (this wire will have 12v + when the key is in the on/acc, and crank position). What you are going to do after you find your proper wires, ( or run them) is to connect your 12v + switched to pin #85. You will then connect a ground wire to pin #86. You should be able to get ground from the dome lights. Your constant 12v + will go to pin #87a. Pin #87 is not used in this configuration. Now from this point on, wiring up the led is very simple. You connect the red lead of the LED to pin #30 of the relay, and connect the black lead of the LED to ground. Now what will happen is this; whenever your ignition is off, your relay is off, and your LED will receive constant 12v + from pin #30. When you put the ignition switch in the on position, your relay will power on and break the connection from pin #87a and #30, and will turn off the LED. Its very simple once you wire it all up. You should be able to buy a SPDT relay at a local stereo shop for about $6. If not, you can get them online from Sonic Electronix and similar places. If you need any more help, just ask.
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