Mercruiser MAG 350 MPI 2010 Bravo to Alpha config swap

[TheCramps]

Hello to everyone,
This year i bought the Mercruiser MAG 350 MPI in order to change my old 5.7 carb merc.
Now my problem is that i wan't to keep my Alpha one gen II sterndrive but the new motor has an ECM programmed for Bravo drives and its not recognizing the signal from shift interrupter .
This swap has been discussed in this thread http://forums.iboats.com/forum/engi...pi-bravo-to-alpha-config-swap?_=1467532423434 but now its closed so i couldn't post there.

I had came up with an idea but i need some help on order to make it work.
I have an electrical engineering background so i made a board with a relay which works as follows:
When it detects a change from the shift interrupt switch it will turn off the engine for some milliseconds.

Now, which i the best way to cut off the engine? The ideal situation would be to have some "kill switch" cable from the harness and when i grounded it the motor will cut off.

Thanks in advance,
Thanos

 

[NHGuy]

I just reviewed that thread. All the experts on there said the Bravo ECM would not allow the shift interrupt on the Alpha. The original poster ended up getting a Bravo drive.

 

[NHGuy]

Then on a search I found this! Go to post #17. I think it's do-able as it stands.http://forums.iboats.com/forum/engi...263-5-7-vortec-2bbl-to-350-mag-mpi-conversion

 

[TheCramps]

Thank you for your answer! I was looking for those diagrams too..

The problem is that the ECM ignores J2-9 because its programmed for a Bravo that don't need the shift interrupt in order to shift-in-out.
My motor had also this jumper between black and purple cables, but even if i remove it the motor keeps running.

 

[Scott06]

I think two ways you can do it

I belive a merc dealer can reflash the ECM to an Alfa configuration. This came out of a discussion I had with a dealer selling and mpi motor that I was considering for a repower.

Get a different shift interrupt or switch. You need one that is normally closed rather than the normally open that is on there. Wire the normally closed in the 12 v positive supply to the coil it will kill the ignition momentarily. I belive Michigan motorz can set you up with the right switch as I discussed this with them in relation to using the Delco ignition set up that they sell.

 

[Scott Danforth]

Just get the ECM reflashed

 

[NHGuy]

The interrupt causes a ground on alpha. Donno how that affects the bravo though.

 

[TheCramps]

No Title

To get the ECM reflashed they asked about 600$..

Scott06 its pretty easy for me to find a normally closed switch.
I think is better to cut the ground from the ignition coil. Im attaching an image for reference.

Do you think that this will work? Is there any chance of damaging my coil or the motor by doing it in that way?

Thank you

 

[Bondo]

To get the ECM reflashed they asked about 600$..

Ayuh,..... Welcome Aboard,..... Sell yer Bravo 'puter, 'n buy an Alpha 'puter,.....

If yer guess is wrong, you may well smoke the 'puter ya got, 'n will be buyin' a new one anyways,.....

 

[TheCramps]

Bondo is it possible to smoke the ECM just by switching on and off the GND of the ignition coil?!

 

[Bondo]

Ayuh,.... Yer the electronics engineer, you tell me,.....

In my experience, any 'puter wants to see what it wants to see, 'n nothin' else,.....

 

[TheCramps]

No i don't think its possible, my only concern is that the ECM might see it as an error and start sound alarm