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Discussion Starter · #1 ·
I tried the search function which leads me to my first question.

Do one-wire alternators have two wires coming out from them?

This is on a 94 Camaro 3.4 V6 engine. There's a big red one on the back of the alt with a 90* rubber boot covering it, like on older cars - this wire is about a foot long and goes to the positive battery terminal (it's hooked to the red battery cable clamp).
There's another red wire, maybe 14-16 ga that is hooked to the alternator by means of a connector. The other end of this went to another connector - don't know what it was connected to.

The engine is on a test stand so it can run without being in a car and I'd like to know where to connect the little red wire.

I've removed 99% of the wiring harness since it'll be converted to a carb/distributor without computer.

Thanks.
 

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One wire alternators only have one wire on them, so that's not a one wire.
How many contacts on the alternator connector? 2? More?
 

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Discussion Starter · #4 ·
Dave,
Thanks for the link. I came across it while searching. If it applies to this, I can't tell.

John,
About the connector with the little red wire - in the alternator part of the connector there are four little male prongs (pins?), in the part of the connector with the little red wire there are four female holes to accept the prongs.

I forgot to mention something about the positive battery cable clamp - there's another red wire, same size as the big one from the alternator, which has a ring terminal. I don't know what it went to either. I'd guess a horn relay.
 

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Glenn.

Modern cars use modern regulators inside the alternator. The 94 version you are talking about, probably is a CS type like John suggested. If it is the regulator is a solid state unit that digitally regulates charging. It even delays (2 - 7 seconds) the rise of the field current when load increases, thus giving the engine management the opportunity to raise the RPM a little.

Regulation is achieved by switching on and off a 400 Hz signal to the field. The duty (10 - 90 %) time dictates the field current.

The connector in such an alternator has 4 connections :
- P (phase, mostly used only internally to determine the alternator is running fast enough)
- S (sense : determines the voltage at the battery as an indication of its status, as well as a indication when the voltage drop in the wiring is too high)
- L (lamp: used to drive the indicator lamp in the dash, sometimes - in even more modern cars - used to tell the alternator is may start charging. Also used to indicatate output voltage is too low or to high.)
- F (field: internally connected to the L terminal through a resistor. It has somewhat the same function. In some applications this is used as a battery feed - throug the ignition switch - for the 400 Hz signal, but some do not).

Because all depends on battery voltage and the electronics are rather smart, a lot can be determined internally. Thus applications may differ in the way the wires of this connector are actually used. You apparently have only 1.


Your red wire is used to 'sense' battery voltage or drive an indicator lamp. Depending on the specific application it will be connected to either the F, the L or the S terminal. Incase of the S you will have to connect the OTHER end to the battery pole. In case of the F you will have to connect it to IGN. In case of the L you will have to connect it to an indicator lamp which has its other side connected to IGN.

Hope this helps.

Rob
 

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Glen,
Can't help you with the alternator wiring but....we have never had a need for an alternator on the test stand that we have. We have run-in marine engines for a good 45 minutes with just a battery and never had a problem. You do need to have the timing etc just about perfect so you dont have to crank forever to get started, but once it fires, the ignition really does not use much power. You could always hook a battery charger up to the battery if you want to be certain.
 

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Discussion Starter · #8 ·
Rob,
Thanks for the thorough explanation. I'll ask at the Camaro site to see if anyone knows if the little red wire is connected to Sense, Lamp, or Field.

Bill,
When you said you don't need an alternator on the test stand, does that mean that there isn't one or there is one and it's disconnected?

I guess I don't really need the alternator, but I do need the alternator pulley so the Serpentine belt will work.

If I ran it with the alternator disconnected should the big red wire be removed from the rear of the alternator?

Thanks.
 

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Glen,
We dont use one at all. Our test stand does not use the water pump so we really do not need any belts whatsoever. It dont think it will hurt the alternator to just run it with no wires hooked up at all.
 

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Discussion Starter · #12 ·
Rob,
Thanks a lot for everything. I looked and it's in the "L" slot, so I'll run it to the ignition.

That's a big help because now I know what to do with it when the engine goes in the car.

I cleaned some of the engine today. We're supposed to have temperatures in the 70's this weekend and I'm going to try to get the block, heads, and oil pan painted Chevy orange while the weather's suitable.
 

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Glenn.

OOPS. I was not thinking for a minute. If your wire is connected to the L terminal, there is supposed to be an INDICATOR LAMP between this red wire and the IGN.

(I have corrected my previous post. I do not see an e-mail address for you, so I can only warn you here).

Inside the alternator the L wire will (electronically) be switched to ground if :
- the alternator is not running with IGN on
- the charging voltage is too low or too high
This ground will light the indicator lamp.

Sorry again.

Rob
 

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Discussion Starter · #14 ·
Rob,
I'll be sure to include a suitable bulp between the alternator and the ignition switch.

Please don't be sorry - you've been a big help.
Electricity has always been like a black art with me.

Thanks again.
 
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