Wiring a universal key-switch?

[greaseball]

Hey, I searched a little and all the answers I found were WAAAAYYY off, so here's the situation-

The stock ignition I'm replacing has 3 wires. Black/red, black/yellow, black white.
I'm ASSuming this is constant power(BAT), key power(IGN), and ground(?) (UNLABELED).

On my "universal key switch" I have 4 location options.
BAT, IGN, ACC (<-- won't be using that one) and the 4th and center post is UNLABELED.

I'm GUESSING that the black/red is constant, the black/yellow is keyed and the black/white goes to the unlabeled.

Using a multi-meter, can someone tell me how to test these theories?

Many thanks!!!

[345 DeSoto]

One of them HAS to be to the "Solenoid/Starter"...usually the center one...

[VirgilHilts]

Put the meter on ohms or better if it has a continuity beeper use that if not 0 ohms will mean you are getting a connection ( dead short = 0 ohms).

Put the key in don't turn it. Attach one of the leads to the first pin on the switch (whichever you want just keep track of which one). Then test each other pin AND the metal body of the switch. You should probably get no beep.

Now repeat that procedure for each position of the switch, crank,run,acc. ( you may want an extra set of hands or have this clamped to something if it is not installed)

Note which pins give you a beep or 0 ohms and in what position.

Now move the lead to the next pin and repeat this whole procedure. Then the next pin and the next. Again noting the connections.

There will be some redundancy with this method but it's a bit hard to type it all out and not seeing the switch doesn't help so for the sake of thoroughness!

Many people assume these switches are simple one pole deals and that power shows up at one terminal in certain positions etc. But often they are a multi connection switch and often one of the pins goes to ground in crank to act as a brake bulb test, hence me mentioning testing to the switch body too.

The one you need to look for is the pin that makes a connection when on crank AND ignition AND accy position. That would be the Voltage IN terminal. The rest will connect to it when in their respective key positions and thus you'll know what their functions are.

[N8B]

What kind of car are you dealing with? I am sure one of us may have a wiring diagram handy to tell you exactly what each is.

[nico32]

Agreed with both statements above, one has to be for the starter. Best to put a tester on it and verify what is what.

[greaseball]

Cool, thanks guys!

* VirgilHilts= NAILED IT! Thanks man!

* N8B= The rides kind of "off-topic" actually....
(*SUPERSECRETSTRUCTURE* and all that, don't want to get anyone upset talking about an "off-topic" ride)


I just noticed the stock switch IS in fact "labeled".
IG, ST, ACC, AM

So I'm guessing the IG goes to the IGN, the ACC post was never connected, and now that just leaves the ST and AM, anyone care to guess what those abbreviations stand for?

[VirgilHilts]

DeVry grad. Better be good for something!


ST = start (AKA crank)

AM is a stumper. That's the one I figured was a bulb prove out.

[N8B]

Originally Posted by greaseball

Cool, thanks guys!

* VirgilHilts= NAILED IT! Thanks man!

* N8B= The rides kind of "off-topic" actually....
(*SUPERSECRETSTRUCTURE* and all that, don't want to get anyone upset talking about an "off-topic" ride)


I just noticed the stock switch IS in fact "labeled".
IG, ST, ACC, AM

So I'm guessing the IG goes to the IGN, the ACC post was never connected, and now that just leaves the ST and AM, anyone care to guess what those abbreviations stand for?

Auxiliary (something or other?)
Crazy question, does your car have an ampmeter?

[Commish]

Since you don't list one labeled Bat., I would say it pulled it's battery power from the amp gauge on the original installation .

[345 DeSoto]

Bet that's it...

[LastChance]

The switch ground itself to the dash when you mount it, so you do not have to worry about grounding the switch(its not really needed). Make sure you have good ground on the frame, body, and engine, it has kicked my tail abunch. Good Luck.

[345 DeSoto]

Does the ignition switch HAVE to be grounded, or will it work with out being grounded?...

[todd_a]

If you are dealing with this one:


Then it wires like this:

[todd_a]

Originally Posted by 345 DeSoto

Does the ignition switch HAVE to be grounded, or will it work with out being grounded?...

Doesn't mention grounding it anywhere on the instructions.

[30dodge]

Ign. switches do not have to be grounded, they are there only to direct the the power to the desired circuit. They can be mounted on wood, metal,fiber glass. or just hang in the air and still work.

[345 DeSoto]

I have a switch out of a boat, and it only has "ST", "IGN","BAT"..thus the question about grounding it...Thanks...

[VirgilHilts]

As others have stated, it does not need to be grounded for its basic functions. Some factory switches ( late 60's Fords) do just to provide a ground source for the brake warning light during cranking.

[Southfork]

The ignition switch in my '65 Impala project works only when it is Not mounted in the dash. Turn the key and nothing happens; Take the switch out of the dash and let it dangle on the wires, and a turn of the key starts the engine right up.

It's been a while since I read the book "Zen and the Art of Motorcycle Maintenance," but the Impala's ignition switch seems counter-intuitive. Why won't it work when it is mounted/grounded in the dash? Go figure...

[Ice man]

Its a switch, so NO ground is necessary on that one. Its just passing current to what ever. If it had a Back light then it would need a ground. Iceman