I have just built a new 540 EFI and I can not get a Mercruiser/Rinda scan tool to read codes on my mefi3 ecm. I know how the tool works, and have used it many times on different boats. Any suggestions on how to get this thing to read my ecm?? Thanks, Jeff Wurl

Hit it on the side of the boat three times and try it again.

Anyone?????

Your ECM may be a replacement mefi 4 , scan tool will not read it.

ECM is the original with GM delphi mefi3 part number 16236999. Thanks anyways, Jeff

I have a 2001 hp 500. I think it is mefi 3
in the repair manual it states ecm units number 840136-1 and below will not have trouble code readability
840136-2 and up will
hope this helps