1 wire alternator install problem.

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Re: 1 wire alternator install problem.

Post by Linda » Mon May 20, 2019 8:07 pm

Check the connectors under the driver side dash. If dirty or loose you won’t charge.
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Re: 1 wire alternator install problem.

Post by JT68 » Mon May 20, 2019 8:44 pm

aclever1 wrote:
Mon May 20, 2019 5:32 pm
Sorry for the confusion, this is a 3 wire GM alt set up. People in the internet kept calling it a 1 wire but it really is the 3 wire set up we have in the wiki.

I was testing things since it was weird that I only have a few volts at the alt on the battery terminal so I disconnected the wire at the fuse and it test at 12.3v, I took the wire off the alt and it was 12.3 but as soon as I touched the alt it fluctuated between 1 and 3 volts. So I grabbed the other alt and grounded it and hooked the power wire to the batt terminal and it stayed at 12.3v so I swapped the alternator thinking the new GM alt was bad. Now with the other alternator on, and car running it was at 12.3-12.5v but when I revved the car it jumped to 35-45v so I turned the car off. This was the one I bought off eBay that was said to be a 1970 Datsun roadster alt but has nothing on it to tell what it really is. It looked just like the GM alt I bought but I guess it's not since it doesn't appear to be internally regulated.

My new voltage regulator showed up from Datsun parts so put the stock alt back on and took it to the auto parts store to have it tested and they say it's still my voltage regulator that is bad. The kid that tested it didn't know what it meant but his computer said it was the regulator or diode that was bad. I have tried a few other regulators so I doubt all of them have been bad. I still think it's an alt problem.

How do I test the voltage regulator? I can keep the old stock alt on if I know the regulator is working or I can swap to the eBay alt and run the external regulator but I don't want to kill another battery. I wish I knew JT sold alts too, I would have bought one and saved time and money.
You've got a lot going on here....

I would bet the new regulator is fine - they get blamed as bad when its really just bad connections or wiring whether in the harness or alternator or wherever..

It does sounds like there could be multiple issues at hand....

I'd suggest to get a handle on what is good an what isn't. You can pm me a photo of the "70 Roadster" alternator an I can decode that mystery.

For the GM alt you bought, suggest just taking it to Autozone or O'reilly or any car electric shop and have it tested on an alternator machine - rule out a bad alternator.

Your easiest play is probably to get the 3-wire gm working wired directly to the battery as I outlined earlier in this thread. You can pm if you want me to help you directly.

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Re: 1 wire alternator install problem.

Post by Lorna c » Thu May 23, 2019 2:13 pm

good luck . you'll get this .
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Re: 1 wire alternator install problem.

Post by redroadster » Sun Jun 16, 2019 6:22 pm

Most parts stores will test free
Does the rotor feel magnatized with a screwdriver?