Volts light problem

[johnson350]

Having an issue with the volts light being on when the key is out of the ignition. Also when you rev the car the volts light gets brighter and brighter. It started doing this a little while before I parked it. But I figured it was just a bad alternator, so i went ahead and totally rebuilt it. Started the car up today with the new alternator, still has the same problem. Volts light is on when the key is not even in the column.

When you turn the key to the on position, the volts light goes out, but comes on again when started. Any help would be appreciated, because I am stumped... :?

 

[pontiacgp]

when you rebuilt it did you change the rectifier cause it sounds like one phase is gone and there is a short

and you might want to read this, I would remove the battery terminal till you fix it
http://www.efiglobal.com/content/includ ... r_2011.pdf

 

[johnson350]

No, thats about the only thing I did not replace.

I just took it all back off and did some testing on the stator to be sure it doesn't have any shorts. It all checks out ok.

Is there any way to check the rectifier with a meter? And you betcha I got that battery terminal off of there. It does seem like a short somewhere inside the alternator, it was warm, kinda hot only after running for about a minute.

 

[pontiacgp]

checking the rectifier (diodes) is easy

[youtube]xgikeXt91vM[/youtube]

 

[johnson350]

I justed checked the diodes and their fine, but is there anyway to check the rectifier itself?

 

[johnson350]

Im sorry if I have no idea what im doing, this is the first one ive ever had apart. thanks for helping me though 😀

 

[pontiacgp]

we all have to start someplace and i started 40 years ago so no need to apologize. One thing to keep in mind rebuilt alternators are not too expensive. I bought a new alternator this summer for $90 . By the time you buy the parts and add up the time you put into rebuilding one a rebuilt or new one sorta makes sense. If it's just a regulator I'll change that but anything else I buy a new one

 

[johnson350]

Thanks again, I appreciate you getting back with me so quick.

This happens to be a rebuilt alternator. About the 3rd one I've put in in the past year and a half. I'm positive the wiring in the car is ok. Seems kinda fishy, this one happened to last a year. I'd just thought I'd try out rebuilding one.

Well I checked continuity between the battery stud on the back of the alternator and the case, and I'm getting some continuity, which tells me its grounding out somewhere in the alternator. Also checked the rectifier bridge, and turns out whatever is causing the short has popped the middle diode inside the rectifier bridge. So gonna have to get a new rectifier bridge. The diode trio is still ok, even after i ran it for about a minute.

Its strange, when i revved the alternator it made kind of a whirring noise, like a bad bearing, but the bearings are fine, i checked when i had them out. I also put in a new regulator and brushes too.

So, looks like I'm gonna have to do process of elimination to find out where my short is in the alternator so I can permanently fix this problem.

 

[pontiacgp]

when I said checking the rectifier was easy that was't meant to imply you should know how to check it. I just meant your in luck, it's easy to check

 

[johnson350]

Oh, yes they are quite easy to check. Just can't figure out why I'm getting continuity between the case ground and the battery post when I check it with an ohms meter.