The charge light came on one day, went on and off again, finally came on and stayed on.
Frustrating... after checking all the wiring, removing and retightening the battery cables and the wires on the alternator, checking ground, the light went out. Thought I'd fixed it. In the time it took to pack up all my tools, went back and started it and the light was on again.
Removed the alternator and battery and had them tested at the local parts store. Both test good.
Rechecked everything, I see on the wiring diagram there are a couple of wires that go to the Engine Control Unit/Module, so I take the ECU out and clean it's connectors by taking them off and on again a few times. Charge light goes out again. I shut off the car and restart 3 times (letting it sit a few minutes between), light goes out immediately when engine starts as it has when things were fine.
Nope, restart car about 10 minutes later and the charge light is on again. No wiggling of wires or tapping on anything makes it change.
I even took out the ECU and resoldered all questionable solder joints (I've been an electronics tech for a number of years). Charge light still on.
During one of the times when it was working, I took some readings. I doin't know how meaningful they are except they tell me that it is not a wiring problem between the alternator and the battery.
The only difference between charging and not, one of the two wires between the ECU and alternator: normal operation, when first started it is about 3.6V, dropping to about 2.5V. Later starting it and the charge light comes on, the same line is now about 1.5V.
But without knowing which way this signal goes, I don't know if the fault is the alternator or the ECU telling it the wrong thing.
I see some mentions here of worn out brushes. Where might I find those in the northwest USA? I've checked a few places like Autozone and it lists them but says unavailable.
Thanks, Steve