Can you post a picture of the ballast resistor wiring? According to the wiring diagram for a 74, the dark blue wire should be attached to same end of the ballast (both top and bottom connectors) with the dark blue/yellow trace wire to the ECU. On the other end of the ballast, the dark green/red trace wire should run to the ECU and the other (brown?) wire runs to the voltage regulator. The diagram shows the dark green/red trace wire on the opposite level of the dark blue/yellow trace. Say the dark blue/yellow trace is on the top row so the dark green/red trace would be on the bottom row and brown would be on top.