Battery light on, but alternator OK

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Usually after starting I tap the accelerator pedal and the battery light goes out.

Today it didn't.

Took out the multimeter, checked voltage at idle 14.25v

Shut off engine, battery voltage at 12.68v.

Restart engine, same results.

Bad ground wire?
With the alternator putting out 14v, shouldn't the light go out?
What else should I check?

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Well I started it again and tested voltage after cleaning all the wire terminals, this time it was 11.8 volts idling.

So I had a spare reman alternator in my parts pile (brand new) and decided to swap it out. I had to change the pulley and bracket since it was from another model engine (maybe a gas even).

After getting it in, tensioning the belt and everything, I went to hook up the wires at the back of the alternator. One of the wires that I took off the old alt. had disappeared!

I looked under the car and found a ring terminal with a short length of blue wire attached to it.
So I spliced in a new ring terminal to the end of the wire, fired it up, and the light is out and 14.4 volts at idle.


But now I suspect that it was the blue wire hanging by just a thread all along, not the alternator. I had the alternator tested last fall and it was good.

[TylerDurden]

I think this is fairly common... The alternator shakes a lot, and the exciter wire breaks inside the jacket. Looks fine, but often acts intermittent.

[Quantum-man]

I guess it's easy to forget how the circuit works if it has the habit of working for 20yrs between acting up.

Useful to remember the battery turns the light on and the alt lead turns it off.

My alternator seems to wait about 5 seconds to begin charge @ 850rpm, or as you say can be blipped by revving