Little help for my car?
 

Hey guys, usually I'm pretty good with electronics and such, but this has me completely baffled. I'm trying to figure out how to wire up a switch for my car. Its a simple on off switch with a LED in it, but it has 5 pins (WTF?). Any help here (that means YOU Brian!) would be greatly appriciated. Basically all I need it to do is turn my interior LEDs on and off. I'm not sure if I want the LED on all the time or not though. I'll have to figure that out later. Anyway, heres a pic.

http://i47.tinypic.com/2dhs0v7.jpg

As you might be able to see, theres a + and -. I took my volt meter and put it on LED and found that the LED is powered constantly (whether its on or off) by the outer two pins, but thats all I can really figure out. :oops:

It's hard to tell from the pic, but the 5 pins are probably as follows: 2 for the LED, and 3 for the SPDT switch; common, normally open (NO), and normally closed (NC).

If I were a betting man, I would say the outermost terminal marked + is the LED anode, the opposite outermost terminal would be the cathode (-). Use an multimeter to verify. Depending on the amount of voltage the ohmmeter outputs in resistance mode, it may dimly light up the LED (when hooked right).

That leaves the three terminals in the middle. Usually, the center pin the common connection, one of the outer pins will be either NO or NC. The other pin would be the opposite; NC or NO. So, hook a meter on the middle and one of the other pins and measure the resistance. If it's infinite, its the NO connection. If so, turning the switch on should make it read 0 ohms (or close to it). Then, do the same between the middle pin and the other pin. The results should be opposite.

Another clue is those three blank spots. I bet those would be for another three terminals for a DPDT switch.

EDIT: Oops, I didn't see the part you wrote on the bottom of your pic. So, I was right. They did this so that you could wire it however you wanted depending on your needs. If you do use it, you will need a resistor or you'll blow the LED. If you don't want to use the LED, just leave those pins disconnected; the switch will still work.

Hmm, I think I'm better off asking this here than on the car forum I'm on, given with you two (squee and Brian) I have an electronics expert and a car guy in the same spot.

Anyway, I have HID headlights on my car, and a standard dual filament halogen bulb that takes care of fog lights/high beams (I'm talking about my G35, FYI). I want to get an HID kit to replace the fog/high beam light, and I was planning to run a "wiring harness" (I'm pretty sure it's a relay). Do you know if the bulbs will have flickering issues?

Sorry for the the threadjack squee...

I think Brian is right about the switch. They probably did that so you can choose whether the LED has power when the switch is on or if it is off.

Thanks Brian! That helps ALOT.

I tested it like you said, and figured it out. :yipi:
I looked EXTREMELY close, and actually, the C1 (labeled C1 since the blanks are labeled C2, NO2, NC2) is closest to the cathode side for the LED.
What ohm resister will I need for a white LED?
And last question, how would you wire it up to have the LED on only when the switch is on? It doesn't seem to light up regardless using the C1 and NO1 or NC2.

No problem on the threadjack man.

As for the HID's, what kind of bulb is it? There aren't to many dual filaments that I can think off. H4 being one of them.

It's an H4 bulb for the Fog/High's. The factory low beam is a D2R (but obviously that'll stay as is).

From what I could find on my research, it's a single filament bulb and switching from low to high (in my case, fog to high) just adjusts a metal shield that alters the beam output. (I'm speaking of the HID's - obvious the stock halogen bulb is dual filament).

I just always read of people having issues with HID's flickering and not turning on and what not, and was wondering if having a relay would prevent this? I'm assuming it would since it would allow direct power draw from the battery, and therefore would not be limited to the power provided by the factory harness.

Squee: The resistor you need depends on the voltage drop of the LED ("Vf" value) and the supply voltage you plan to use. Here is a page that should help you out: http://scriptasylum.com/rc_speed/_led.html

To have the LED on when the switch is on, you'd have the + of the LED/resistor go to whatever terminal the load is tied to.

BP: I really have no idea. Haven't done anything with HID, nor do I know what they are like. Sorry man. :oops:

I don't think it would be a problem, but if it were, a relay probably wouldn't work to keep flickering down, but might. I just doubt it would help. I have HID's, and if you get a good kit, flickering shouldn't be a problem. Mount them well and you should be good.

Ok, so the + of the load goes to the common, and the - goes to the normally open, then the anode with a resistor goes to the common as well, and the cathode goes to?

That's fine Brian. Am I at least correct to assume that a relay works by acting as a switch between and input and output, and turns on and off with when the relay is triggered by a (smaller) current on the "switch" leads?

Yeah, pretty much. Just think of a relay as a device that can use a small signal to control a high current/voltage circuit.

Yes, your right. The relay works as a switch so to speak. It should have 4 pins, one goes to the + of the battery, one goes to ground, one goes to the + of the HID kit, and the other goes to the + of the stock harness, and then the - of the HID kit goes to ground as well if I'm not mistaken. I could be wrong, but I just wired one up the other day and I'm pretty sure thats how it went. The only problem I could see would be grounding the HID, cause I think it says somewhere in the instructions that came with mine not to ground it.

If I follow what you're saying: No. You're probably overthinking it.

First, put the LED in series with the resistor.

Then, you are effectively placing that LED/resistor "circuit" in parallel with the rest of your load/circuit.

Sorry, I'm still a little confused. Its late. :lol:
Like this?

http://i48.tinypic.com/nyxl5g.png

Well, that the switch layout. If you're asking how to hook the LED/resistor up to the switch:

1: Supply voltage goes to the NO terminal.

2: One end of resistor goes to C.

3: Other end of resistor goes to LED anode

4: Cathode goes to ppower supply ground.

5: If you are hooking up other things to the switch, hook the circuit to the C terminal.

BTW: Are you sure the C is where you have it in the picture? Usually, the common terminal is in the middle with the NO and NC on either side.

I think I get it. :oh:

Basically I just need a on off switch for my interior LEDs. Its pretty much directly powered. I just cut the wires that go to the 12v plug and use the positive to go in to the switch then the switch goes to the + of the control box for the LEDs, then the - of the LED control box goes to the - of the 12v plug.

Edit: Yup, I'm sure.