Pelican Parts Forums - Alternator problem

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Alternator problem

I need some help to diagnose my alternator problem, on a '76 carrera 3.0.

My alternator light is dim at idle and gets brighter when the RPM increase.
I had 13.8V at the battery, so this tells me the alternator is charging.

I bought a new voltage regulator from our host, I thought it would be a good idea to replace the old one (probably mechanical). The old one is a white marchal.
With the new one in place, the light was even brighter, and I measured up to 17.0V at the battery ! So I put the old one back.

I've read many posts and I think I understand the charging diagram. The fact my light is on means there's an imbalance between B+ and D+.
With lots of volts at the battery, I suspect a weak D+ output.
What would cause this ? Bad diodes ?

Maybe I have 2 issues, a weak D+ and a lazy voltage regulator ?

What other tests should I do ?
I've never removed the alternator so I'm not sure it's the one that I expect (marchal) in there.

Where can I measure the D+ voltage ?

Thanks !

-Guillaume

Quote:

Originally Posted by tabasco (Post 4558875)

I bought a new voltage regulator from our host, I thought it would be a good idea to replace the old one (probably mechanical). The old one is a white marchal.
With the new one in place, the light was even brighter, and I measured up to 17.0V at the battery ! So I put the old one back.

Are you sure you hooked up the wired correctly? Did you double check to make sure you had the right one?