Correct Way to Wire a GM Alternator

[Hillbilly Racing .30-30]

So I know this has probably been covered, but we all know how well the search tool works on this site..... Anyways, chevy 350 with stock 3 wire alternator. Thought I had it working but it turns out it does not charge. What is the correct and simplest way to go about it?

[generaldoum]

I don't know if its what you are talking about... But I did mine like that. Pretty basic and simple.

[Hillbilly Racing .30-30]

That's basically how I did mine, but I didn't use the #1 pin or a switch or anything. I have an 8 gauge wire from the alternator charge stud straight to the battery. Then I have a jumper from the #2 pin that's tied into the charge wire

[generaldoum]

You didn't put a wire from #1 pin the battery positive? If so, that's your problem. Put a 12 gauge wire from that pin to the battery, and put a switch on it. Look on the second paragraph under the diagram, on my picture. It will basically explain why this wire is necessary.

[generaldoum]

It's always a good idea to put an "idiot light" as shown on the diagram to know if your engine is running. And also, I always use a separate switch for my alternator. Keep in mind that when the car isn't running and the alt. switch is in ON, it draws power from the battery...

I'm no wiring/alternator expert... But like stated, that is what I read here and it's how I did mines... So feel free to comment or add more detailed information...

[generaldoum]

Like is said, I only put a light to know if the engine is running, but it's not necessary... No resistor is needed. But for safety, you could add an fusible link on your 8 gauge wire, close to the battery.

So... 8 gauge wire from "BATT" to battery positive (with fuse link). 8 gauge (10 gauge is also enough) jumper wire from #2 spade to "BATT". And 12 gauge wire from #1 to battery positive, with a switch (and light, recommended) and it should charge. (engine should be grounded on battery negative of course...)

[Hillbilly Racing .30-30]

My #2 pin jumper is 12 gauge, but I think that should still be enough shouldn't it? Also, how do you hook up you light? Do you do it inline or do you ground it and just splice in the hot wire to the light?

[generaldoum]

Yes, 12 sould be good for the jumper cable. For the light, I splice and ground. Not inline.

[Hillbilly Racing .30-30]

Thanks! I will add that in tonight and see what happens.

[seventyonehemicuda]

GM is the simplest/easiest of all alternators!

step 1.-twist all 3 wires together
.....thats it...

-connect to + side of battery before heat
-disconnect from battery after heat (or it will slowly drain battery).

no extra switches, loops of wiring nothing at all
you can run the wires through old heater hose if you like for extra insulation to stop from shorting on body steel

[STROMI 121]

Everyone says it will drain the battery. Been lucky I guess. Never unhooked it or had a dead battery.

[generaldoum]

I had this problem once. That's why I'm using a different wire with a switch. Never had issue since then. But I guess its all personnal preference/decision.

[seventyonehemicuda]

Jun 9, 2015 11:23:26 GMT -5 STROMI 121 said:

Everyone says it will drain the battery. Been lucky I guess. Never unhooked it or had a dead battery.

I've never tested it... I've just always believed that "they" were telling me the truth.

[demodave216]

I've left mine on and had it drain the battery.

[STROMI 121]

Gonna have to dig out the ole multimeter and check for parasitic draw now I guess.