The alternator and brake pad lights are on when the engine starts on my 84 300TD. As soon as I rev it up they go off though. In my past experiences that usually means the alternator isn't self exciting as it should, which is not part of the regulator. Is this the case with these Bosch alternators? If so I'll replace the whole thing.

-Tad

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1995 G320
2003 C230 Kompressor Coupe
2005 ML500
2007 ML350

Is your idle speed up to spec?

- Jeff Miller
190DT

Check you regulator the brushes have worn down, the need to speed up the engine is a good sign. The springs get weaker the shorter the brushes are.
There was a post i remember some where that some one found brushes and just replaced them. If not get new regulator for $40.00 and install easy job.
Bill

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94 dodge cummings,86 ford 6.9,75 mbz 240d[ sold], 82 mbz 300sd,83 mbz 300sd

Closer to $30:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1CQ0J3JZ41R70JEYV6&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1984&product=F4010-30110&application=000272331

You can install it in 15 minutes with a screwdriver.

You need to keep an extra voltage regulator module on hand anyway, so maybe you should go ahead and get one now and give it a try. I'm sure you've read that the brushes are integrated into the voltage regulator module.

When the voltage gets a little low due to alternator charging issues, the indicator lights start acting strange.

And the most likely alternator charging problem is brush wear.

[To me your problem sounds like brush wear - and that's also the cheapest solution - try that first.]

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

I agree. Checking that idle speed is up to spec is a cost free first thing to do. If that's okay then proceed as other's have suggested.

The idle speed seems to be fine. I'll try swapping the regulator from one of the parts engines.

Thanks guys.

-Tad

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1995 G320
2003 C230 Kompressor Coupe
2005 ML500
2007 ML350