I wasn't referring to the ECM, I was referring to the MMDC. It's my understanding that if your boat has analog gauges then you they will not process the digital signal from the MMDC.
Thats completely right but you wouldn't need it to process through the mmdc. Basically your temp, rpm, etc would all be direct while your other functions would still be through the mmdc. My oil pressure etc is all direct and not using the plugs from the mmdc.