Alternator

OK, look, we are back to the very basics. For a minute, forget everything except the very basics. You have the ignition switch "in there" and you have the bulkhead connector.

The ignition switch supplies power in run, accessory, start, etc

There are only THREE switched lines coming from the switch through the bulkhead

1--start, yellow or yellow tracer on most cars, comes right from the ign switch, through the bulkhead, and to one of the push-on terminals of the start relay. Hot in start only

2--Coil resistor bypass, traditionally brown, comes direct from the ign switch, through the bulkhead, and hooks to the coil + side of the ballast resistor. Hot only in start, not "run."

3--MOST IMPORTANT "run", traditionally dark blue, comes from the ign switch, through the bulkhead and is the wire we have been talking about. Hot ONLY in run, NOT start.

THIS IS THE ONLY switched "hot wire" that is "hot" in run.