Issues with alternator swap

[monte85]

Hey all. I have searched and read as much as I can find about doing this swap. Last year I converted to fuel injection, electric fans and serpentine belt. I originally used the brown alternator wire until one day it stopped charging. After checking the wire, I found it no longer had 12 volts to it so I started using the old choke heater wire. It was fine until about a month ago. My original alternator suddenly started over charging. Being short on cash I picked up a used one and put it in. It worked for a day and also failed. This one put out no voltage. I then picked up another alternator, this one is remanufactured. Drove the car all week to work until Thursday night, when I notice the gauge isn't showing that the car is charging. So I get home, get a meter and start checking things. I unplugged the alternator connector checked voltage on the brown wire. Yup voltage is there. I plug the connector back in and the alternator starts singing. Now its putting out 13+ volts. I will say the connector came out kind of easy, like it might not have been plugged in completely. Anyway, these are my questions.
Is any of this just random chance?
Did I just get a series of questionable alternators or is something now blowing them up? I have measured resistance on the brown excite wire, and I get about 500 ohms. I measured from the connector to the battery positive with the ignition on, correct? I want to solve this because I miss driving the car.

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[darbysan]

I'm not an expert on this, but IIRC the brown wire runs to the gauge/idiot light, and gives the alternator's regulator just a slight load (50 ohms). On mine, there is a short red wire (10 ga) that runs from the charging post to the connector. This is the excite wire. Been that way for over 10 years with no issues. The way you measured voltage on your brown wire would be the way to measure for the brown wire going to ground. If you wanted to check for 12V on the brown wire, you should be checking to the negative post, or any ground point on the engine or body.

Here are some wiring diagrams. Note the short wire from the charging post to the connector.
http://www.amphicar.net/darrellgaddy/De ... Si_Alt.htm

 

[monte85]

I believe the wire going to the stud on the alternator is for voltage sensing. i'm more interested in the brown wire and how it needs to be. the brown wire is the one that needs to be connected correctly to make the cs series alternators run. I no longer have an idiot light since I converted my dash to gauges years ago. I never had any charging issues then. but as I stated before, something happened to my original brown alternator wire(lost 12 volts somehow) so I started using my old choke power wire. I want to know if I am testing the resistance of the wire correctly and if I have to much or not enough resistance to make the alternator work properly. I checked the resistance measuring from the brown wire to the positive with the ignition on and got 500 ohms. so far what I have read in my searches, I need anywhere from 35 to 800 ohms to make the alternator charge. I hoping that I am reading things correctly and I was just having some bad luck with alternators.

 

[monte85]

I have connected my brown 12 volt wire to the f/i terminal on the regulator. This is apparently how the 91 camaros are. The f/i terminal has built in resistance between it and the l terminal (about 350 ohms).

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