Replacing alternator diodes? Yes, I've searched.

eolson · 06-30-2015, 02:08 PM

I've searched and read a ton of threads regarding my problem and I think I've narrowed it down to faulty alternator diodes. I'll figure out how to test them to find out for sure, but assuming that's my problem, can they be replaced?

I have the dreaded battery light on with the key off and can't find anything else wrong. I'm going to go through my wiring again but it charges fine as soon as the engine is running. I had the alternator rebuilt last summer, new bearings and a voltage regulator, and it all seems fine except for wherever I have current escaping (?) with the key off.

Somebody somewhere is rebuilding these, they must be since I can buy a remanufactured alternator? Also, the Bentley manual essentially tells me to replace it for this exact problem, so there's new parts out there somewhere. I'd hate to get a whole new alternator if all I need is $10 worth of diodes from RadioShack and a little time with my soldering iron.

Anyone?

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Targalid · 06-30-2015, 02:23 PM

Try this:

Can this SEV Marchal alternator (aka Mr. Sparky) be repaired?

turbo951 · turbo951's Garage

They can be replaced... If your saying it looses mainly at night when the car is of ,yes it's a diode.

eolson · 06-30-2015, 04:04 PM

The light comes on as soon as I turn the ignition off, so I assume something is "open." I put everything back as it was before having the alternator rebuilt so I assume my wiring is ok, but I'll double check that. I can't imagine what I could have in the wrong place to cause this problem?

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eolson · 06-30-2015, 04:05 PM

Quote:

Originally Posted by Targalid

Try this:

Can this SEV Marchal alternator (aka Mr. Sparky) be repaired?

Saw that one, thanks.

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harvardma · harvardma's Garage

I just had mine replaced by a local shop for $127. I am sure if you look you can find a shop near you. I fried mine when I started the car as the battery was too deeply discharged after it had been sitting for a long time. The diodes still tested OK with a meter from the outside of the alternator as it was only half the diodes that had gone.