1984 BJ60 - Charge Light and Buzzer (1 Viewer)

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I'm riffing on this recent thread:


Similar but different.

Truck wasn't driven for a few months. Started driving and noticed dash voltage was low. Car driving fine I ignored it until a week later the charge buzzer started buzzing. Multimeter found batteries at 12.2. Truck at idle showed batteries at 12.2, so alternator not outputting. Overnight trickle charge, then took out alternator and took it to alternator place. They are weeks out but said it tested 'bad', sold me a voltage regulator and I swapped it in.

Replaced vr, brushes looked good. Back in motor and installed my cigarette lighter voltage meter. When engine running the batteries get 13.7 or so, then after a few minutes its outputting 14.35. So I think thats how the truck always worked, seems like new vr got alternator into a good state. I wish I understood why alternator behavior changes over time.

My cigarette lighter meter is all over the place, voltage rises with revs until it reaches 14.3 at 1800rpm or so, so its at least stable on the freeway and my batteries won't go dead.

Any time rpm drops below 1k the charge buzzer starts up, but in a non-linear way.

Whole experience makes me realize I've no idea how the alternator is connected to the car.

I've cleaned connections, also tried grounding different things together with a jumper cable just to see if anything helps but nothing makes a difference.

I've studiously ignored the wires under the dash. Seems like a bad ground under the dash? What do I look for?

Does anyone have a diagram of how the dash charge light works?
 
This should help you checking out the wiring.
alternator int.ext..jpg
 

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