Question: How do I tell if my alternator is failing

[RevPat]

I have a 1981 Corvette. Recently the battery light came on at a very low glow while idling and a brighter glow while driving at about 40 miles per hour. I was told the alternator was failing and should be replaced? Is this correct or is it another issue. recently had starter replaced battery is good

 

[Vettehead Mikey]

Measure battery voltage at idle, highways revs (2000ish RPM) and while the engine is off.

 

[BigJimZ16]

There is a good chance that the "diode trio" in the alternator is bad. It is pretty inexpensive and easy to change, while apart changing the brushes would make sense too.

 

[RevPat]

I have a 1981 Corvette. Recently the battery light came on at a very low glow while idling and a brighter glow while driving at about 40 miles per hour. I was told the alternator was failing and should be replaced? Is this correct or is it another issue. recently had starter replaced battery is good

Thank you for your advice to both of you

 

[6880 Mike]

Most of the generic auto parts places can test your alternator, usually for free.

 

[RevPat]

Most of the generic auto parts places can test your alternator, usually for free.

Thank you for your reply, it was the alternator.
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