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How to Wire Alternator ?


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The CS130 alternators use a four-connection plug; however, for the purposes of a changeover into a vintage car, you will only be using two of the four connections. The connector will be marked “PLFS” or “PLIS.”

 

Depending on the system, you will only be using the “S” and “L” or the “S” and “I” terminals. “P” is the phase connection for externally powered accessories, such as a tachometer or hour meter, and can be used as an option. “L” is the alternator indicator lamp circuit and in some systems will be the ignition connection. “F” is an external field monitor connection. “S” is the main power distribution connector. The “I” connection (when present) is for ignition and connects to the ignition switch (keyed on/off switch).

 

If you have the PLFS connector, it may be necessary to adapt the “L” connection. On a charging system with an “ALT” bulb, you can connect the ignition switch wire directly to the “L” terminal. If the system does not have an “ALT” bulb, it is necessary to install a 50 ohm diode in the wire leading to the “L” terminal. You can purchase a diode and solder it inline or you can purchase a jumper harness with the diode already in it (Delco 8078 or GM # 12102921). This harness has the 10SI connection on one end and the CS130 connection on the other.

 

If your alternator has the PLIS connection, the ignition wire goes directly to the “I” terminal without the need for extra resistance. This 10SI to CS130 jumper connector is also available from Delco (8077) or Painless Wiring (30707). Many installers have used a short jumper wire from the “BAT” post on the back of the alternator to the “S” terminal; however, the proper way to make this connection when making your own harness is to go from “BAT” to the main fuse box, relay or power feed and then back out to the “S” terminal. This extra step will ensure proper external voltage sense readings.

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Did you find a plug? I wouldn't solder directly to the terminals. 

 

That looks lime a used alternator, did is come with your engine? Should be able to find a donor plug in a yard, GM built millions of those cars.

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14 hours ago, AMC86Kid said:

so its a CS130 Alt

 

 

the red wire goes to Plus of Batt

the white wire is the exciter and its internally regulated

 

Correct. It's an internally regulated Delco alternator. Whatever you do, DON'T solder any wires to it. If you can't find the connector, use individual spade terminals or something.

MJ_Alternator_Diagram.JPG

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Google Delco 8077 or Delco 8078. Summit Racing has an SI to CS harness for $8.00. They also sell the harness with the appropriate diode for $25.I would copy and pasts links, but my tablet sucks rocks that way.

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Well I tried to wire it up 
started the engine 
and got no power out of the Alt 
i wonder if it’s bad 
gonna have to go get it bench tested

Probably not wired correctly. Be good to bench test it anyway to be sure.

I’ve seen the two wire plugs fail, only charge when the wires or plug were moved. My guess is the plug or jumper you built isn’t quite right yet. I’d order one of those kits mentioned earlier just to have it simplified.
At one point it was a bigger pain to convert from the old alternators to the newer style seems like enough people wanted to upgrade they made kits to make it easier.



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Well I got it tested and it passed 

I think I didn’t spin it fast enough to engage the stator 

 

I soldered on female connectors 

slide them over the pins 

and hot glued it so it won’t short out

 

501F6B7F-FD8C-4D64-A3A2-C8D4C08E51C6.jpeg

 

Is this a dummy light ?

5EE15D7C-10B0-46D6-8C6F-BB096417584B.jpeg

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Ok I did some more tests and here is what I believe 

 

8D1442AF-A445-48AF-A583-15965E812848.jpeg

5C858049-844D-448F-8FE1-8D43AA762E26.jpeg

 

I'm testing between the negative terminal on the battery and the positive post on the alt 

 

at idle speed I get .5 and when a gas up to around 2000-3000 rpm I get 1.5 volts 

so I think my alt is bad and the guy that tested it didn’t know how to test it correctly 

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On 4/19/2020 at 8:25 PM, AMC86Kid said:

Screen Shot 2020-04-19 at 8.24.01 PM.png

 

I can't tell from your photos, but unless you have 12+ Volts to the Bat+ stud and a Ground to a negative post on a battery, like in your diagram above, it won't work. 

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