The Stovebolt Site Forums The Shop Area The Electrical Bay Alternator Harness

I currently have a one wire alternator 12V on my 54 4400. The harnesses I see advertised (American Classics, Chevy Duty, Jim Carter etc.) are they designed to work with the one wire system or with conventional GM alternator or does it make no difference.

1-wire alternators are made for tractors.

You would do better to use a 3-wire ... read about the differences Here

And for proper wiring of a 3-wire, check out my notes Here

kb3csw,
Brief explanation of 1, 2, and 3-wire alternators.

MAD electrical comparison of 1, 2, and 3-wire alternators. (I think Alan Horvath links to this on his website, too.)

If you already have a one-wire alternator and want to keep/use it, it will work fine with the Chevy Duty wiring harness (for use with a 1, 2, or 3-wire alternator, as I recall) - you just use one of the alternator wires.

If you want, I will post a picture of the one-wire set-up this evening.

By the way, you can also use a one-wire alternator with the standard/original wiring harness (set up for a generator). However, if I were buying a new harness, for a vehicle that might one-day have an alternator, I would get a harness that would work with a 1, 2, and 3-wire alternator.

Tim

A two wire (also referred to as a three wire) is the one you want to use because it will begin charging as soon as the engine starts. A 1-wire alternator typically needs about 1200 rpm engine speed to excite and begin charging. Because our old trucks do not idle that fast the charging will not begin until later. You will notice the symptoms as being much like the generator you took off....

The wiring harness you are looking for is called a DA Plug and besides helping the alternator to begin charging when the engine starts it also makes the engine shut off with the original ignition switch. Because an alternator is able to produce current at idle it will flow backwards and keep the coil hot even after the ignition switch is turned off. The result is the engine still keeps running even with the key off....a big source of social embarrasment!!. That is why ignition switches were changed to the "accessory type" in the 1960's. They could use the accessory terminal to isolate the alternator terminal from the rest of the terminals on the switch thus stopping the flow of current back to the coil.

Fifth Avenue manufactures the DA Plug and they are also thru various dealers.

Thanks Randy

Hey, Randy

That's great info, bro'! Thanks.

I put a diode on the #2 wire to my alternator, which keeps the electricity from going back towards the ignition switch and makes for a total shut-off when I turn my ignition key off. A nice improvement!
SEE HERE

Thanks for your suggestions and information