Thanks for the replies, guys.
So, if I get this correctly, I can either purchase the CodeMate code reader for $39 (
http://www.rinda.com/marine/marine.htm#merctool), and read the LED flashes to get the MEFI error code (but not know the exact component that triggered the code),
or spring for the USB -> MEFI cable for $195 (
http://www.obd2allinone.com/sc/detai...item=mefiscan1) and use the free software (
http://www.tunerpro.net/downloadApp.htm) to read the error codes, and much more.
Am I missing anything?
It doesn't look possible to build your own MEFI cable, must be some circuitry involved.
Thanks for the education!