Did you unplug the ECU when checking voltage at the disconnected ballast connectors?
How I check...…
1) Disconnect both sides of the ballast.
2) Disconnect the ECU plug.
3) Attach volt meter to Ign 2 ballast plug and ground.
Zero volts in "key off" position.
Battery voltage in "key start" position.
Zero volts in "key on" position.
4) Attach volt meter to Ign 1 ballast plug and ground.
Zero volts in "key off" position.
Zero volts in "key start" position.
Battery voltage in "key on" position.
How I see the system working.
Start circuit acts as a "hot" wire giving full battery to the positive side of the coil and "hotter" spark to the plugs on key start.
Run circuit is battery power reduced through the ballast resistor to not cause the coil overheat as it runs.