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Location: DFW
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Alternator light "Dim"??

When I drive my car at night, I can see that the alternator light is on, but very dim.

You can not see the light during the day, unless you cup your hands around the light.

The car is registering about 12.5v with the engine off, and about 14v with the car idling.

Everything else is working properly.

Is this the early signs of an alternator issue? Or should I not be concerned until the light comes on bright?

Thanks,
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Kris

1979 911 SC ROW
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Old 11-26-2006, 02:18 PM
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That is exactly what happened with my 87. The light finally came on full bright. I had the alternator rebuilt and I re-installed. After rebuild, the light was out and everythting has been fine since.

If your alternator needs rebuilding, find a good, reputable shop in your area. A rebuild is a heck of a lot cheaper than a new replacement...

Mike
Old 11-26-2006, 02:59 PM
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The 'dim' warning lamp syndrome is NOT an indication of impending alternator failure!!! It is the result of corrosion [and buildup of Voltage drops] at all of the connections in the warning lamp circuit ... along the path of the Blue D+/#61 wire.

Clean all of the Faston connectors in the path from warning lamp to alternator brush holder with vinegar & Q-tips, rinse with distilled water, then blow dry with compressed air. That path includes the 14-pin connector at the electrical panel in the engine compartment!
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Old 11-27-2006, 10:09 AM
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I JUST WENT THRU THE SAME PROBLEM

I just went thru the same thing with my 74. The alternator was not bad and I had good grounds. It was my regulator.

Although in the end, I had my alternator rebuilt, because it was not putting out to its full potential and I got a new battery because the sides were bulging. Now the new regulator took care of the problem, but do yourself a favor and have the alternator looked at to make sure its 100%. The extra work the alternator does to compensate for other down falls causes extra wear and tear....

Dont replace the alternator without replacing the regulator, but yours is internal, I dont think that should not be a problem.

Also check the voltage at the battery (with it hooked up) with the car at 3000 rpm, it should be 13.82 minimum. Its just an indication of what the charging system is putting out, its not a diagnostic problem solver..
The light can be caused (most likely) by not having a good ground from the alternator to the engine block, transmission to the chassis or battey ground to the chassis. How ever it can be caused by a diode going bad on the diode plate on the alternator.

Early S Man is correct, clean your contact FIRST. This is the most likely problem.
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Old 11-27-2006, 11:26 AM
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Jeez, I have to apologize for jumping the gun on my reply to you Kris. I hope that cleaning all the connectors as Warren suggests will take care of the issue with your dim alternator light. That is certainly some very fine advice.

In the case of my car, the light started dim, went to full bright over a couple day's time, and I also had a low output reading. The shop that rebuilt my alternator tested it and confirmed that it was "bad". Therefore, a rebuilt alternator was in order and that fixed things for me.

Good luck.

Mike
Old 11-27-2006, 11:38 AM
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Thanks for the help.

I will check the connections and grounds tonight.
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Kris

1979 911 SC ROW
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2001 Honda Odyssey - Kid Karrier
Old 11-27-2006, 03:11 PM
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Old 11-27-2006, 03:11 PM
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