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tr6turbo
Dale Knapke
Sidney, Ohio
(169 posts)

Registered:
08/24/2008 09:44PM

Main British Car:
1972 Triumph TR6 Ford 2300, 4 Cyl Turbo

Question, Alternator Wiring
Posted by: tr6turbo
Date: January 15, 2013 09:39PM

I am using a Ford G3 alternator .One of the wires going to the alternator is hot in run only. This is the wire that has the warning light if you run one. If you do not use a warning light do you have to put a resistor in it's place?


DC Townsend
David Townsend
Vermont
(406 posts)

Registered:
11/21/2007 12:22PM

Main British Car:
'78 B (almost done) 30-over SBF, dry sump

authors avatar
Re: Question, Alternator Wiring
Posted by: DC Townsend
Date: January 16, 2013 11:41AM

On a 3G, the short answer is, yes, you need to run a resistor - whether you use a warning light or not, With the lamp, the resistor is run in parallel to the lamp circuit so, in the event the lamp burns out, the circuit will still have the proper resistance. Attached is the wiring diagram. You can get the resistors at any Radio Shack type store.
schematic-3G-ALT_wiring.gif


tr6turbo
Dale Knapke
Sidney, Ohio
(169 posts)

Registered:
08/24/2008 09:44PM

Main British Car:
1972 Triumph TR6 Ford 2300, 4 Cyl Turbo

Re: Question, Alternator Wiring
Posted by: tr6turbo
Date: January 16, 2013 05:03PM

This was kind of a loaded question. Does anyone know why we need the resistor? I have been running without a resistor or warning light for more then 10 years and have not had any problems.
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BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Question, Alternator Wiring
Posted by: BlownMGB-V8
Date: January 16, 2013 06:02PM

It was to switch on the field circuitry originally I think, or to switch off the sense wire circuit which can drain the battery, but with the advent of 1 wire alternators they've learned to do without it and have incorporated this feature into most regulators. Earlier Japanese alternators are a notable exception (not sure about the most recent ones) where a relay is used in the circuitry to the sense wire to disconnect it when the key is off.

Jim


DC Townsend
David Townsend
Vermont
(406 posts)

Registered:
11/21/2007 12:22PM

Main British Car:
'78 B (almost done) 30-over SBF, dry sump

authors avatar
Re: Question, Alternator Wiring
Posted by: DC Townsend
Date: January 16, 2013 06:57PM

I think Jim is right on the field circuit switch. And to come clean on this, when I've used a 3G, I've run them both with and without the resistor circuit without any noticeable difference. That said, I've been running 1-wire unit for the past few years making the use of a resistor, moot. But my answer to the posters question still stands - the accepted way (not the only way) to wire the 3G is with the parallel resistor circuit.


tr6turbo
Dale Knapke
Sidney, Ohio
(169 posts)

Registered:
08/24/2008 09:44PM

Main British Car:
1972 Triumph TR6 Ford 2300, 4 Cyl Turbo

Re: Question, Alternator Wiring
Posted by: tr6turbo
Date: January 16, 2013 08:30PM

David, I agree that it switches on the field circuit. One thing I do notice is that if I let the ignition on in run (engine not running) for awhile the alternator gets warm, not hot and the battery drains. Does that happen in cars with the resistor? Does the alternator use the difference in sence voltage and the run voltage when using a resistor to some how stop the voltage drain while the switch is in run and the engine is not running. I guess I need to try it and see.

Thanks for the comments.


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