Strange starting issue
They are different sources. The 67 ballast resistor has a hot in start and a hot in run. The power to the ecu , along with the voltage regulator is hot in both start and run.
You lost me there, bud
There are only two contacts on the ign switch, "run" (ign1, dark blue) and "bypass" (ign2, brown)
The run circuit (dark blue) goes cold during crank, the brown should feed "hot" 12V to the coil, and BACK through the ballast to the ECU
If the dark blue "run" feed to the ballast is bad/ disconnected, you won't get anything to the ECU
During crank, the brown bypass/ ign2 will feed power directly to the coil side of the ballast, AS WELL AS "back through" the ballast to the junction point of the dark blue, and feed power to the ECU
So a light dawns--It suddenly occurs that I'm not sure the "run" circuit goes cold on newer (72-3) factory electronic ignition cars
(On mine, I'm now running an HEI module with no ballast, so no longer applies.)