Thread: Alternator
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Old 03-20-2017, 02:29 PM   #4
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
Thanks for the reply Vette. Ill list off my answers with their questions you have.
1. You are correct with your assumption. The power for the cab is coming from the jblock.

2a. Initially, the fuse would blow right when i started the truck. But i figured it was the connection at the BATT stud shorting from a loose connection or the stud itself being loose. I replaced the stud and it seemed to fix the fuse blowing on start up. Then i put it in drive took off down the road and looked at my voltage gauge and it was reading way low. Come to find out the fuse blew.

3. From my previous thread, i believe you helped me with, you suggested the 40amp maxi fuse. it's been running perfectly well since then. I have tried the fusible link setup but it seems to get hot quick. Thats why i have the 4g with the maxi.

The tests from my OP arent showing the numbers that i received. My numbers were coming out to 2x what they show.
Alt BATT stud to battery + = .2
Alt case to battery - = .4
Sense term to battery + = .3
4. I checked the accessory CB with key off. Positive cable removed and the test light in between the cable and the post.

5.The engine continued to run whenever the fuse blew. The voltage just dropped.
I tend to agree with you that the alternator stud was what blew the fuse and it may still be the culprit. You may have damaged the diode pack in the alternator which could provide a short to ground in the alternator output circuit.

I say this because you have not had major damage out of the battery supply circuit after the fuse blew, (the engine continued to run but the voltage dropped). Obviously the voltage will drop after the alternator quits charging, but the thing to note is that the fusible link didn't melt after the alternator was out of the picture. I would take a voltage reading on the alternator output and make sure it wasn't overcharging and also that none of the diodes were shorted out.

Based on what you've said, I think you've isolated the problem to the alternator. I'm not sure that Autozone or any of the other auto parts stores could test it and determine that it was bad. It should show up as overcharging or shorting with their equipment and the test is free so it might be worth the effort.
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