Alternator light instead of gauge - how do I wire it?

Yes I've searched but something tells me that squirrel will post a thread link that he posted to that will answer my question. S o here goes...

I have a GM one wire alternator, an It's A Snap harness and want to run an alt light in lue of a guage. How do I go about wiring up that little light? The harness has the brown exciter wire that I'm guessing I'll be using for this. In my search, I found this thread but it's a little vague towards the end on what is being done - http://www.jalopyjournal.com/forum/showthread.php?t=48863&highlight=alternator+wiring+light

Can someone answer this, please?

Thanks,
Vance

 

i'd be interested in knowing this as well.. My harness is a scratch built with a radio-shack diode between the alt and ignition...

 

Sorry. One wires don't have a pin on them for the idiot light. The three wires do. I believe it is Pin 2 (white wire), and you run it to one side of a light bulb, and run the other side to your ignition.

Pin 1 on the alternator is usually just folded over and mounted to the Bat terminal.

With a 1-wire all you can do is run a voltmeter, or build yourself a voltage comparator that triggers a light on a low voltage.

 

In your case, just add a light somewhere between the diode and the ignition (assuming the diode is in the direct path to the alternator), or you could even remove the diode. The diode is to give a voltage drop so the alternator starts up, but the light gives enough of a drop as well.

With a diode, your system obviously uses a three-wire alternator.

 

Thanks man - that's what i thought... i'm looking foward to getting rid of this ugly ass voltmeter i grabed out of an ambulance..

 

It is the #2 terminal that is jumped to the big terminal.

The attached file shows how to wire the light.

 

there is also a voltage sensitive diode which lights up red below 11.5 v, yellow 11.6 to 12.2 or so and green above 12.4, a local indy bike shop sells them. or you can build a simple setup like this one: http://members.ozemail.com.au/~bobpar/ledvolt.htm

Larry

 

There seem to be two different kinds of "one wire" alternators, some have a plastic plug in the hole where the other two terminals would be, others have the two terminals....my understanding is that if it has the two terminals, you can connect an idiot light to it.

I run 3 wire alternators in all of my stuff except my bulldozer, and that's only because one of the trucks we got had a one wire alt laying in the bed.

Idiot lights are good. at least for idiots like me that don't look at the gages

 

Crap! 50:50 chance and I got it wrong

 

Thanks squirrel. I knew I could count on you. I shoulda just PM'd you.

I have one of the one-wire alternators with what looks like it should have a plug going into two male connectors. Will I blow up anything if I hook up a light to these male connectors and it should have been reversed?

I've been a long time believer in lights over gauges. I believe you'll see a light come on out of the corner of your eye WAY before you'll see a needle drop.

Vance

 

I doubt you could hurt anything in the alternator by reversing the connections, but I guess you'll find out.

and if you did, or the light doesn't work (and you are sure you wired it correctly) you can just get a normal 3 wire alternator to replace it.

That diagram that ModelAVette posted should show you how to do it.

 

I already printed that image AND saved it to an external HD for future reference.

Thanks.
Vance

 

I have the chilton's book it was scanned from

 

Sounds like you have a 3-wire (the Bat plus these two make 3). You can't hook a light-bulb up backwards.