1975 to 1985 Chevy pickup Delco 10SI

Looking for a little clarification so I don't mess this up in the future.

The wire that connects from the output terminal to the 2 wire connector is feedback voltage to set the output voltage level right?

The other one that goes to the ignition switch is for exciting the field to start the generation process right?

What is the function of the diode?

The diode prevents current from the diode trio inside the alternator intended to be used as field current as needed by the internal voltage regulator from backfeeding into the ignition system when the ignition switch is turned to "OFF". This can keep the igntion system operating, and prevent the engine from shutting down.

You can use an "idiot light", OR a resistor, OR the diode in that lead.

Any ONE of the three options is sufficient.

Besides preventing the engine from continuing to run when the ignition is switched "OFF", the diode, "idiot lamp", or resistor protect the innards of the alternator from possible damage under conditions where there's current backfeeding OUT of the alternator's #1 terminal into the igntion system or battery.

On sytems where an "idiot light" will NOT be used, I use the diode, as it can be simply taped up in the wiring harness, as it doesn't generate much heat, as the resistor option will, under certain conditions.