"Periodically when the car is started instead of all the lights on the panel lighting up for a quick second only one light, usually the 4th gear disengagement arrow. . . "

That is strange, because the same Key ON voltage that gives you the Arrow light, is fed to all the other warning lights too.

If it were only the Charge warning (and 4 others) failing, that would cause your battery charging problem. Because besides the Charge warning light, 4 more lights* are connected so that Key ON current from all five bulbs is fed to the Alternator D+ terminal, and then to ground thru the Voltage Regulator, brushes, and alternator ground wire.

This is called "pre-exitation current" and is required to initiate voltage generation as the alternator starts turning. Without this current, you basically run on the battery till it gives up.

With all the alternator work you've had done, it seems that the small red wire must be secure at the D+ terminal, and that the external ground wire (Blue, on my '93 940) is in place. The "signal" leaves the instrument panel on pin 16 of 18-pin connector "5/1C". But so far I'm unable to trace the routing to the alternator.

* The other 4 lights are:
• Parking Brake
• Brake Warning
• Bulb Failure Sensor
• Washer Fluid Level

However, based on the voltage routing at the panel, I can see where (if the fuel gauge climbs with Key ON) the switch voltage may be getting as far as the Arrow light, but is then stopped by an intermittent break or defect on the printed circuit board. That would take out all the rest of the lights, including the 5 you need for alternator foreplay. That's my best guess.

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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.