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2001 330xi
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686 Posts
Discussion Starter #1
Hi all,

I'm looking for switched power at the relay box that contains the fog relay, horn relay etc.
I'm having problems finding which of the many wires there I should tap into. Can somebody help out?

Cheers,
-fana
 

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2000 E46 323i, 3.0L and 2.0L Z3's
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386 Posts
Go to NewTIS at Car selection . Enter the last 7 digit of your VIN number into the search box and it will select your car. There are wiring diagrams in NewTIS. These will help you in finding a switched power supply.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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1,531 Posts
Power distribution diagrams are very elusive in new tis.
They're in there, just need to dig deep.
If you can't find it, I'll dig in on Monday when I get back to the shop.
 

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2001 330xi
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686 Posts
Discussion Starter #4
I tried finding it on NewTis, but failed. I found the fog and horn relay descriptions , but not whether there is switched power I can tap into.
How do I find out which one is switched? e.g., Fog light
 

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I'm not sure if I can explain this very clearly, but I'll try. There are two large wires (maybe 10ga or so) that run to that area from the ignition switch. Those are solid purple and a solid green. These wires originate in the ignition switch plug and energize a couple different sections of the fuse box. You can tap them directly to get switched power. One of them is activated at key position 1 and then they are both active at key position 2. I don't recall in which order they come on when you turn the key.

Alternatively, you should be able to tap any one of the smaller gauge wires that branch off those two wires, provided it's the proper gauge for the load you're attempting to add to that circuit. The main purple wire from the ignition feeds into a series of fuses and the wires coming from that (fused circuits) are mostly purple with yellow stripe. The main green wire from the ignition feeds through fuses to mostly green with blue stripe I believe.

An exception to the switched power with those, if I remember correctly, is the horn relay. It's always on and has a purple/yellow wire going to one side of it.

Regardless, test whatever wire you're trying to tap with a multimeter at all key positions to make sure it's hot when you want it to be, and not when you don't.
 

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2001 330xi
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686 Posts
Discussion Starter #6
I'm not sure if I can explain this very clearly, but I'll try. There are two large wires (maybe 10ga or so) that run to that area from the ignition switch. Those are solid purple and a solid green. These wires originate in the ignition switch plug and energize a couple different sections of the fuse box. You can tap them directly to get switched power. One of them is activated at key position 1 and then they are both active at key position 2. I don't recall in which order they come on when you turn the key.

Alternatively, you should be able to tap any one of the smaller gauge wires that branch off those two wires, provided it's the proper gauge for the load you're attempting to add to that circuit. The main purple wire from the ignition feeds into a series of fuses and the wires coming from that (fused circuits) are mostly purple with yellow stripe. The main green wire from the ignition feeds through fuses to mostly green with blue stripe I believe.

An exception to the switched power with those, if I remember correctly, is the horn relay. It's always on and has a purple/yellow wire going to one side of it.

Regardless, test whatever wire you're trying to tap with a multimeter at all key positions to make sure it's hot when you want it to be, and not when you don't.
Thanks! That should do it, very good info. And thanks for reminding me to simply test with the multimeter.
-fana
 

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Yep, some are purple with blue as well. Glad you found a solution.

Interestingly enough when you break down the fuse box and actually look at all the wiring where it terminates you can get a better idea of how power is routed. I first thinned all the wiring on my project, then ultimately gutted all factory wiring and started fresh. Learned quite a bit doing that.
 
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