interrupt switch with new engine

[sgwill122]

I just replaced my 2003 5.0L Carbed Mercruiser with a 2012 5.7 MPI by Indmar, I thought I was at the finish line today but the final step was splicing the brown line off the ECM into the shift interrupt switch. But I found the interrupt switch is doing exactly opposite of what I need. It is open in the normal position and closed when shifting. This means my engine has no spark unless I depress the interrupter switch. Is there a interrupter switch that will do the opposite(normal closed and open when shifting)? The Clymer Merc manual indicates that older EFI interrupt switches operated differently than carbureted versions. Anybody know if merc makes two different versions of the interrupt switch(closed versus open in the normal position)? I called a few part shops but unfortunately the guys I talked to did not know.

 

[Bondo]

Re: interrupt switch with new engine

I just replaced my 2003 5.0L Carbed Mercruiser with a 2012 5.7 MPI by Indmar, I thought I was at the finish line today but the final step was splicing the brown line off the ECM into the shift interrupt switch. But I found the interrupt switch is doing exactly opposite of what I need. It is open in the normal position and closed when shifting. This means my engine has no spark unless I depress the interrupter switch. Is there a interrupter switch that will do the opposite(normal closed and open when shifting)? The Clymer Merc manual indicates that older EFI interrupt switches operated differently than carbureted versions. Anybody know if merc makes two different versions of the interrupt switch(closed versus open in the normal position)? I called a few part shops but unfortunately the guys I talked to did not know.

Ayuh,.... There are Both, but off the top of the noggin', I don't know what used which....:facepalm:

 

[Don S]

Re: interrupt switch with new engine

Did the shift plate and shift interrupt switch come with the Indmar or the Merc?
As far as I know, all the shift interrupt switches are normally open and close when activated. I assume the Indmar instructions said to use the brown wire, to the shift interrupt switch, but where does the other side of the switch go to?

 

[sgwill122]

Re: interrupt switch with new engine

The indmar did not include a shift plate/interrupt switch so I am re-using my merc shift plate/switch. The indmar diagram shows the switch is spliced into the middle of the brown wire on the ecm. The diagram is a bit sparse on instructions, it just says the interrupt switch is normally closed(opposite of what I have). I was hoping that merc made both flavors for the same shift plate so I can just replace my switch with a normally closed. If I have to I could add a relay to reverse the behavior but would prefer to keep it simple.

 

[Don S]

Re: interrupt switch with new engine

Did you check your switch with a meter to confirm if it is a NO or NC switch?

 

[boatguya1]

Re: interrupt switch with new engine

I just replaced my 2003 5.0L Carbed Mercruiser with a 2012 5.7 MPI by Indmar, I thought I was at the finish line today but the final step was splicing the brown line off the ECM into the shift interrupt switch. But I found the interrupt switch is doing exactly opposite of what I need. It is open in the normal position and closed when shifting. This means my engine has no spark unless I depress the interrupter switch. Is there a interrupter switch that will do the opposite(normal closed and open when shifting)? The Clymer Merc manual indicates that older EFI interrupt switches operated differently than carbureted versions. Anybody know if merc makes two different versions of the interrupt switch(closed versus open in the normal position)? I called a few part shops but unfortunately the guys I talked to did not know.

I'm not at work so can't look it up to verify, but this what I think. The 2003 carb motor has the roller on the end of the arm type switch that is norm open. The 2012 will most likely require the pushbutton type switch in the norm closed variety. My guess is that you'll have to buy a complete bracket assy to make the new style switch work. Once again I'm not certain that this is the case.

 

[Don S]

Re: interrupt switch with new engine

Does anyone know for sure if the new style switch is NO or NC?

 

[Pete104]

Re: interrupt switch with new engine

Why not just wire the interupt switch to the coil?

I'm looking at a service training book & obviously that's the way they want things done. So far I've only got to ECM 555.

YES, there are different switches. What module does Indmar use?

 

[Don S]

Re: interrupt switch with new engine

Why not just wire the interupt switch to the coil?

You can't do that with EFI and still control the spark with the ECM.
No one here knows what Indmar has for the distributor. Or what the wiring does. This is an aftermarket engine hooking up to a shift interrupt switch.

What we need is to have someone with the new style shift interrupt switch to check it and find out if it's actually NO or NC.

 

[sgwill122]

Re: interrupt switch with new engine

It has a MEFI 5 ECM. Attaching the wiring diagram I was given as part of the installation instructions. I am re-using my original merc shift plate and switch(which is the source of the problem). I want to use my free day tomorrow to start breaking the engine in so I may goto radio shack and wire in a relay that is NO and will get activated by the interupt switch to close. Not sure if the slight lag will impact shifting much.

 

[sgwill122]

Re: interrupt switch with new engine

Attaching the manual as the picture is getting reduced. Page 9 has the wiring diagram.


View attachment Indmar-Quest.pdf

 

[Pete104]

Re: interrupt switch with new engine

Then go with "boatguy" suggestion, I believe it will need the entire shift plate also. BUT. It still needs to be connected to the module. I've got colors but they are Mercs & I'll bet that Indmar is slightly diff. The new plate would have a "Gear Position" switch as well as the interupter.
Your right with the ECM controlling spark.

The switches on the FEI engines NC since about '04. Not sure which ECM was in play when it happened. The later switch does NOT have the roller on it. It's comes to more of a point. Aslo fits the arm a little different & along with that, I don't think it will mount to the original holes.

 

[sgwill122]

Re: interrupt switch with new engine

This is what my shift plate/interrupt switch looks like. Can someone point to a depiction of the 'new' EFI switch?

Mercruiser Shift Interrupter Switch Kit 864363A 1 | eBay

 

[sgwill122]

Re: interrupt switch with new engine

I bought a NC relay from radio shack and had the interupt swith activate it. It worked perfectly today, i was able to get 4 hours done on my break in. I will call around tomorrow and see if i can find a NC switch.

 

[alldodge]

Reposting the pic so others may see it better next time