Fluctuating neg. to ground on ignition coil
Finally got time to do some measurements:
The ignition coil is getting between 7 and 7.7 volts at + when running at idle, it's marked with 12 Volt, I have yet to remove the ignition coil to see more text on it.
Resistance between + and - in the ignition coil is 1,5 Ohms.
My readings at the ballast resistor:
Battery is getting 14 volt at idle.
ECU is branded "Standard":