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Discussion Starter #1
Hey guys I have a quick question. I have an alternator that has a 3 wire setup. I also have an EFI harness and it has a single wire for my alternator. Do I connect that wire to the battery contact of my alternator? Any info.helps and thanks!
 

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like this you mean?
 

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Discussion Starter #3
alternator.jpg This is the harness I have for the alternator. However, the EFI harness I have has a single alternator wire that is green. Do I attach that single wire to the battery side of the alternator? Or do I connect it to the battery side of the starter solenoid?
 

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What generation alt are you running? That harness looks like its for a Gen 1 externally regulated alt??? You EFI harness will probably be designed to support a Gen 2 (Fox body style) or Gen 3 like I am running. Both of these are internally regulated and only need to be excited (OH MY!!!) by the cars ignition circuit...
 

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Discussion Starter #5
If I bought a 2G or 3G alternator with the 1 wire setup, what should I do with the harness that is coming from the body?
 

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If I remember correctly when I did the EFI I got a three wires alternator, had to keep the stock voltage regulator and connect like the stock wiring diagram.
 

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Discussion Starter #7
So I should probably just put the 1 wire from the EFI harness onto the battery contact of the alternator or the battery contact of the starter solenoid, correct?
 

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IF you were to run a 2G or 3G alt the green wire you are concerned with should be a keyed 12v wire to excite the alternator. IF it is then it would be connected like the diagram Bob provided. It SHOULD be the "Hot in Run" lead. You will need to add a resistor or charge light to it per Bob's diagram.

Could you be more specific as to what wiring harness you are using? Are you re-wiring the entire car or is this an add-on EFI harness?
 

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Discussion Starter #9
I'm using a wiring harness from.Ron Francis that was premade for the EFI conversion.
 

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Wiring the 3G into an earlier Ford using a separate alternator and regulator is a simple process. The 3G unit has five wires on the back of the case, a large battery connection marked BAT+, a small high-voltage spade terminal encased in a gray housing and a three-terminal voltage regulator plug-in connector with the terminals marked A, S and I. The new wiring procedure is completed as follows:

  • Disconnect the positive and negative battery cables.
  • Install the new unit in the existing alternator location (several units do not have the threaded hole on top; in this case, a nut and bolt would be used instead of the original bolt).
  • Locate the "S" terminal wire on the three-wire connector (usually black and white); this wire is to be connected to the high-voltage spade connector.
  • Connect the "A" terminal wire from the same connector (usually yellow and white) to the BAT+ terminal.
  • Connect the "I" terminal wire (usually a green and red wire) to your existing "On-Run-Start" wire from the starter switch.
  • Slightly off center on the back of the new 3G alternator is a threaded hole where you install your chassis ground wire.
  • Use a length of 6- or 8-gauge wire and two eyelet terminals to create a new lead, connecting to the "BAT+" terminal on the alternator at one end to the battery-positive terminal of the starter solenoid at the other, incorporating a circuit breaker with a rating of at least 100 amps. Ford solenoids are normally mounted next to the battery; the larger post that is closest to the battery is where your positive battery cable connects to the solenoid as well.
Once you have completed the wiring, it is no longer necessary to use your existing four-wire voltage regulator. You can now use any 3G single-wire alternator to power your original charging system.
 
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