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Old 02-06-2014, 04:07 PM
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one wire GM alternator

I would like to install a GM one wire alternator on a 302 Ford, has anyone done this? If so could you post how to wire?

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Old 02-06-2014, 05:52 PM
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Run the wire to the battery or starter or the starter sol. Any battery source that is nearest the alternator.
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Old 02-06-2014, 06:14 PM
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Old 02-06-2014, 06:25 PM
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one wire alternator

I'm not a fan of the one wire alternators. I had one on my Plymouth but when at idle or at a stop light the lights would dim. I switched to the standard three wire setup and it cured the dim lights at idle situation.
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Old 02-06-2014, 07:25 PM
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Yes, do it the right way. 3 wire is the only way it should be wired. Read about it here...
MadElectrical.com - Mad Enterprises
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Old 02-06-2014, 11:33 PM
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Been running one on my 302 Ford several years,no problem. Run a 6 gauge cable like Ford's use off the solenoid from battery positive to the alternator and it's done deal, however for extra security I also run a ground strap from the alternator bracket to the frame. I have done this on several other cars and always positive results, most one wires are 100 amp so 6 gauge is preferred no less, if you have one of the higher output units go to 4 gauge.
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Old 02-07-2014, 02:50 AM
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Quote:
Originally Posted by 38project View Post
I'm not a fan of the one wire alternators. I had one on my Plymouth but when at idle or at a stop light the lights would dim. I switched to the standard three wire setup and it cured the dim lights at idle situation.
still running the headlights through the dash harness and light switch...... put the headlights on a relay and take the load off the dash harness and your car will love you.. and they'd not dim.. and they'll get a full 14.3 volts..
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Old 02-07-2014, 12:12 PM
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The late Doc Vette on this forum was my mentor on relays,one of the best explanations can be found here:Watson's StreetWorks Click on Tech tips,then click on "A current topic" Some folks do not like the fact that you must rev the engine at first to "excite" the one wire alternator with about $3 of Radio Shack parts you can easily make it a two wire that will "excite" right at start-up.
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Old 02-07-2014, 12:18 PM
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Quote:
Originally Posted by JeffB View Post
Some folks do not like the fact that you must rev the engine at first to "excite" the one wire alternator with about $3 of Radio Shack parts you can easily make it a two wire that will "excite" right at start-up.
For exactly NO extra Radio Shack parts, you can simply buy a stock three wire alternator (usually for less money than an aftermarket one-wire) and use that (stock 94 amp 12SI alternators and 105 amp CS130 alternators are readily available from RockAuto). I find it instructive that GM, who is constantly trying to save every penny possible when building a car, has NEVER used a one-wire alternator in a production vehicle. That's a lot of copper that could be saved if the one-wire really worked in all situations, so the message is that it doesn't.
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Old 02-07-2014, 01:16 PM
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The 02 Camaro LS1 that's sitting in my shop is about as close to "one wire" as you can get (also has a "turn on" wire that goes to the ecm) and I believe the similar era trucks just used the alt idiot light to "turn on" the alt, but was otherwise one wire. one wire has always worked for me [shrug]
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Old 02-07-2014, 01:26 PM
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Originally Posted by Northstar T View Post
The 02 Camaro LS1 that's sitting in my shop is about as close to "one wire" as you can get (also has a "turn on" wire that goes to the ecm)
So it's NOT a "one wire" alternator...

Yes, you need an exciter wire, whether controlled by the ECU or directly from a voltage source as in the older alternator. The ECU control, by the way, is for increased mileage, as the ECU can turn the alternator off and on as needed, depending on load and state of charge. Feel free to install that not-really-a-one -wire-alternator in something older, but don't expect it to work without the ECU and all the sensors that go with that.

Now, back to reality, you really only need two wires for a 12-SI or CS130, the main battery wire and the exciter wire. The other sense wire can be simply run to the threaded BATT post on the alternator. It's not ideal, but it's good enough. I've had a CS130 in my 62 Olds wired this way for three years now. Of course, running the sense wire all the way to the junction block produces a more accurate voltage level, but unless you have sensitive electronics (like EFI), the fluctuation probably won't hurt anything.
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Old 02-07-2014, 01:32 PM
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Quote:
Originally Posted by joe_padavano View Post
So it's NOT a "one wire" alternator...

Yes, you need an exciter wire, whether controlled by the ECU or directly from a voltage source as in the older alternator. The ECU control, by the way, is for increased mileage, as the ECU can turn the alternator off and on as needed, depending on load and state of charge. Feel free to install that not-really-a-one -wire-alternator in something older, but don't expect it to work without the ECU and all the sensors that go with that.

Now, back to reality, you really only need two wires for a 12-SI or CS130, the main battery wire and the exciter wire. The other sense wire can be simply run to the threaded BATT post on the alternator. It's not ideal, but it's good enough. I've had a CS130 in my 62 Olds wired this way for three years now. Of course, running the sense wire all the way to the junction block produces a more accurate voltage level, but unless you have sensitive electronics (like EFI), the fluctuation probably won't hurt anything.
could you list "all the sensors that go with that" so I won't miss anything?
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Old 02-07-2014, 04:21 PM
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X2 with Joe. While I don't know of any sensors for the ECU controlled alt, other than the ECU it's self which senses demands and lapses and adjusts the alternator as needed.

I've never been a fan of the one wire, and at speed it works fine, idling not so much. Basically a one wire has been internally wired like a good old fashioned 3 wire.

Terminal #1 from the alt goes to the one side of the idiot light on the dash. The other side of the idiot light goes to a switched 12v source (hot when the key is in the run position) This is the exciter wire and tells the alt to start producing juice. The idiot light does not get a ground wire, it gets a ground from the internal regulator in the alt when the alt isn't spinning. That's why it lights when the key is turned to run but the engine isn't running, and it goes out when the engine starts. You do not need a light, you can run it to a switched 12v source that's hot in run only. This is how mine's wired as I have a digital dash with LEDs as indicators, LEDs will not work as alt fault lights as they are polarized.

Terminal #2 from the alt goes to the hot side of the wiring system, normally it’s spliced into the hot feed leading to the fuse box. This is the sense wire, it tells the alt to produce more or less juice depending on the demands of your electrical system. GM used a splice well away from the alt to take advantage of the resistance of a long run of wire, to act as a buffer for the demands on the output etc......

The large lug on the back of the alt is the output wire or charge wire and is normally tied directly to the pos post on the battery via a large gage battery cable. Some people tie this to the starter to clean up the engine compartment, I've never seen a neg result using the starter lug.
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Old 02-07-2014, 04:48 PM
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Quote:
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X2 with Joe. While I don't know of any sensors for the ECU controlled alt, other than the ECU it's self which senses demands and lapses and adjusts the alternator as needed.
I'm with you. I just wanted to know what sensors Joe thought there were. it's the devil in me I guess. all LS1s use the CS anyway, but even the later RVC system didn't use significant additional sensors. the ECM just used the signal provided to control other existing sensors (IAC etc).
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Old 02-07-2014, 06:27 PM
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one wire alt.

If you go with a 1 wire alt make sure to run a smaller pulley as it needs to excite itself by rpm and will charge better at idle with acc on. Only prob with the 1 wire besides is it will draw a very small amount of current while not being used so best not to park it for 2 months with the battery hooked up without being run a bit.
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