Can’t figure out what plug and where it connects on PCM GT40

[Marinshamrock]

I can’t seem to figure out what this plug is for and what it plugs into I traced it back with the volt meter and found it’s grounded on the connections I marked with a sharpie on the ecm if anyone know please let me know it might be the source of my loping idle

[Jonny Quest]

You may want to give this a try on www.CorrectCraftFan.com and see what those old-school guys say. You may want to provide a bit more info, such as engine model year and any issues / symptoms you may be having with the engine.

JQ

[Nautiquehunter]

Does it still have a distributorless ignition ? The big conector looks like it plugged into the coil pack.

[mpost]

Look at this diagram.
https://planetnautique.com/CorrectCr...entHarness.pdf

the pins you have marked on the ecm harness look to be 20,40,& 60 which are ground, and 8 & 30. Pin 8 looks to go to the fuel pump pressure sensor?

[gary s]

Green wire is the S.L.O.W. system. Should be plugged into a green wire leading to the dash light located near by the 8 pin engine to boat harness

[gary s]

Just saw your screen name. Whats the story with a GT40 and a Shamrock? I'm in the process of putting a 40 in my Shamrock 20ft WalkThru as well.
You won't obviously have a green wire going up front to a light. The S.L.O.W. system senses if you have an overheat or low oil pressure and puts the engine into a safe mode which limits RPM and turns on the light on the dash.

[Marinshamrock]

Thanks guys for all the info would the slow system make it pipe at idle if the wire was not connected

[Marinshamrock]

Also Gary the GT40 in my shamrock 200 Cuddy makes the thing fly is so over powered I’ve got it up to 45 on gps fully loaded and it was terrifying and if I didn’t have 2 people a live bait tank and a 300lbs cooler with wind it would have probably gotten up to 50+ I’ve got a speed prop for it but have no plans of putting it on