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Discussion Starter · #1 ·
I have the light on.

Its 100% on at idle. When I rev it it dims to about 50% but does not go out. And its only three months old. http://****************.com/smile/emthdown.gif
Any ideas? All the search results I've found so far don't mention the light dimming down but never going off. I'm

 

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Re: Alternator diagnostic help needed. (All VW All the time)

Check the cluster plugs and the dash grounds. Dim light that never goes out is usually caused by wiring problems in the exciter circuit, shorted diode or a bad regulator.
Pull the alternator and go have it tested. the regulator could be bad.
Just because it is 3 months old means nothing these days. Your chances of getting a bad new or re manufactured part is very high. Some are bad off the shelf.
In general for starters and Alternators I always just take a good core to a local rebuilder and have them rebuilt. They do it correctly, replace what they say they are going to replace and Never had one go bad....
 

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Discussion Starter · #4 ·
Re: Alternator diagnostic help needed. (JUS_GT_EYEZ)

Got 12.2 volts while running at the battery. Does not change while reving, at all. Voltage actually goes up to 12.4 when I shut it down.
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I pulled it and as soon as my wife comes home, I'm gonna take it up to Autozone.
 

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Discussion Starter · #5 ·
Re: Alternator diagnostic help needed. (All VW All the time)

Autozone results.
Lamp/Diode - FAILED
Regulator - FAILED
Rectifier - FAILED
How reliable are these guys? It struck me on the way home that they could rig the test results to FAIL all the time so they can sell more.
No, that couldn't be, all business' are totally honest
 

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Re: Alternator diagnostic help needed. (JUS_GT_EYEZ)

Yep. your test verified it.
Toast. Should be at least 13.5 V with the car running.
You havent run the engine with the battery disconnected have you? Disconnecting the cables with the car running is a sure way to fry them.
 

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Re: Alternator diagnostic help needed. (GTIdaho)

If there is not at least 13.5 VDC at the positive terminal of the battery, then the alternator is not charging. When you measured the voltage, you were only seeing the amount of voltage in the battery as the alternator was not charging.
Cheers, WWR.
 
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