Thread: Alternator
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Old 03-21-2017, 12:32 AM   #8
VetteVet
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Join Date: Jan 2005
Location: Kalamazoo, Michigan
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Re: Alternator

Quote:
Originally Posted by ShinyC10 View Post
I still have warranty on it I believe. Just didn't want to go trough paying for shipping and turns out it's totally okay. And no it's the one for 140ish. Also i did a diode test on my old alternator and my current one and they both came up with the same results: position lead on the BATT stud and negative lead on the case reads nothing. And the negative lead on the stud and the positive on the case reads 10.51
Your test is right and it's not showing the diode pack is grounded to the case.

Did you ever test the output of the alternator when the engine was running before the maxifuse blew? Red lead on the output stud and black lead to case looking for 13 to 15.5 volts.

If you are getting 16 plus then the alternator is overcharging and putting too much current through the MF and causing it to blow.

As long as you're not showing a short to ground through the alternator, I think I would run a bypass wire from the alternator to the junction without the maxifuse, and read the alternator output. Turn on all the accessories that you have and read the meter. I could be that you are simply using too small a Maxifuse or you need the fusible link. Most of our year vehicles do not use a fuse or a fusible link in the charging wire to the junction but everything from the junction is fused.

Yours is newer so they may have started using them when they changed the alternator routing to the starter solenoid.

I have been assuming that your truck has the 12 SI alternator so is that correct?
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