Relay Question [Archive] - Forum


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The Reamer
10-16-2005, 06:30 PM
I would like to use a relay to power some items in my car. I have relays setup for my DRL/ALC mod. I need to change the 12v source for that mod. I just got an MP3 hard drive with a headunit and I have several LEDs I want powered.

So I have a switch connected to 2 relays (the relays are only connecting wires when powered, not powering any accessories).

I have an MP3 HD with headunit.

I have several LEDs.

I would like to power these 3 things when the car is "ON" and use a relay to do it.

I believe using the Sunroof 12v wire would be sufficient for powering these 3 things.

I have two 5-pin relays. I'm not sure if I should use one or the other. The pins are setup differently.

One is setup where the 30 pin connects to 87, and when powered the 30 pin connects to 87a, and I assume, depending on its use, 86 is 12v and 85 is ground.

The other relay is setup where 86 and 85 are the same as above, but when powered the 30 pin connects to both 87 and 87a.

From what I've read and searched, you pretty much have to use two 12v sources in one relay. You need a source to power the relay, so that you can send the 2nd 12v source to whatever you want to power.

So with the 2nd relay I listed, I figured 86 is ground, 85 is 12v+, 30 is the sunroof 12v and both 87s are what I want to power.

Is that the correct way to do it? And doesn't that defeat the purpose of using the use a seperate 12v source in order to connect a different 12v source to power something? I guess if you had a bunch of relays powered by one 12v connection, then it would.

Anyhow, any suggestions would be appreciated. In the near future, I plan on installing the Angel Eyes fog lamps (w/ the LED ring). Would I be able to safely connect it to the sunroof circuit along with the items listed above?

My LED specs are: Probably only use 5 for now


thanks for any input

The Reamer
10-16-2005, 08:46 PM
damn it.....i have a really good track record....every damn thread i make gets a ton of views but not one response, so im gonna break the record with my own response.......

and if u didnt understand my post....then here

i have 3 things i need to power when the car is ON. I want to use a relay to power them. What do I do? What 12v wire should I tap into besides Radio wire? Relay gurus.....give me your best shot

10-17-2005, 08:06 AM
How much power are you looking to grab? Does not seem to be alot.
LEDs take about nothing.
MP3 Player - replacing the stock HU?
If thats all you have then the 12v radio should do alright.
You could always tap the cig lighter; just have to remember to shut off the mp3 player when you get out... and have the leds on the radio lead.

If you want a whole bunch of mods like that, might want to add a relay block. Some one had pics of how they added them to there engine bay. I am doing some searching but can't find it.. sorry to say.. Nor am I a relay guru..

The Reamer
10-17-2005, 08:40 PM
Sorry.....all this would be in addition to my cd deck, so i dont want to use the radio wire. The mp3 unit (omnifi dmp1) does not show any electrical specs, but i dont think it uses too much power.

I'd rather have it connected to an IGN or BATT source, so it's only on when the car is "ON".

This happened last time when I made my own version of the DRL/ALC mod. I asked and asked, and no one would help and ended up figuring it out myself. (i.e. I setup 2 relays, so I could switch between stock setting and mod) I posted a diagram along with it.

Like I was saying.....just like the DRL mod, I'll probably have to figure this one out on my own again. My threads are cursed. It's no big deal. I was just hoping that someone could shed some more light on this subject, so I didn't have to worry about making a few errors here and there.

Thanks for the reply JUAN....

The Reamer
11-05-2005, 07:17 PM
Figured it out.....plenty of wiring, soldering, couple of distribution blocks and done. just need to mold radio bezel for custom fit and thats it.