Shift interrupt switch

[makinhay1]

I have a boat with mercruiser 3.0 liter motor. Bought boat used. When I got it there was no shift interrupt switch on the shifting assembly. It looks as if there are two places it could be installed.
I purchased the plunger type switch that checks out to be normally open type and it seems to me like it should be the opposite of that. So question is, am I installing in wrong place or is there switches that are normally closed?

 

[Bondo]

I have a boat with mercruiser 3.0 liter motor. Bought boat used. When I got it there was no shift interrupt switch on the shifting assembly. It looks as if there are two places it could be installed.
I purchased the plunger type switch that checks out to be normally open type and it seems to me like it should be the opposite of that. So question is, am I installing in wrong place or is there switches that are normally closed?

Ayuh,...... Welcome Aboard,....... 'bout what vintage is this 3.0l motor,..??
A serial number is the best way to tell,......
What drive is on the boat,..??

 

[1960 Starflite]

Mine is the lever type switch (1979 3.0).
The switch is normally open, as yours is. When shifted under load the switch is made (closed) which momentarily grounds the points so gearing can release.

 

[alldodge]

Can be NO or NC and depends on which ignition system you have. As Bondo mention, having the serial number should verify unless a prior owner change the ignition

 

[makinhay1]

Ayuh,...... Welcome Aboard,....... 'bout what vintage is this 3.0l motor,..??
A serial number is the best way to tell,......
What drive is on the boat,..??

Serial number is B915133. Alpha outdrive. Boat is a 2005. I hadn't thought about the motor possibly being changed out But the previous owner has done some modifications. The wiring has had some work so when I added the shift interrupt switch I put in the wiring going to the coil.
Wiring is not my favorite thing to tackle so any help is appreciated.
i installed the interrupt swith with the plunger point to the V on nuetral interrupt assembly. I did this per the Seloc mercruiser manual.

 

[makinhay1]

Serial number is B915133. Alpha outdrive. Boat is a 2005. I hadn't thought about the motor possibly being changed out But the previous owner has done some modifications. The wiring has had some work so when I added the shift interrupt switch I put in the wiring going to the coil.
Wiring is not my favorite thing to tackle so any help is appreciated.
i installed the interrupt swith with the plunger point to the V on nuetral interrupt assembly. I did this per the Seloc mercruiser manual.

Wrong serial number. Its OWO50471

 

[makinhay1]

Wrong serial number. Its OWO50471

Another correction. The plunger would be in the V of the activating lever assmebly. If set according to the manual, the plunger on switch would be open so I get no current to coil. If it was normally closed I think it would work.

 

[alldodge]

You have EST ignition
One side of the interrupter connects to ignition powered 12V
The other side interrupter goes to distributor

It should be a NO switch to only apply 12V when shifting from in gear to out (neutral)

 

[makinhay1]

You have EST ignition
One side of the interrupter connects to ignition powered 12V
The other side interrupter goes to distributor

It should be a NO switch to only apply 12V when shifting from in gear to out (neutral)

View attachment 414169

I just tested this. With the interrupt switch wired in but not installed i tried to start motor and motor would not start. Pressed plunger in on switch and motor will start. My understanding of these switches is NO = no 12v, NC = 12v. ???

 

[alldodge]

Another correction. The plunger would be in the V of the activating lever assmebly. If set according to the manual, the plunger on switch would be open so I get no current to coil. If it was normally closed I think it would work.

There should always be 12V to the coil.

I just tested this. With the interrupt switch wired in but not installed i tried to start motor and motor would not start. Pressed plunger in on switch and motor will start. My understanding of these switches is NO = no 12v, NC = 12v. ???

The switch does nothing to supply voltage until to the single wire going to the right side plug until shifting into neutral.

You sure you have a NO switch and not a NC one?

 

[makinhay1]

There should always be 12V to the coil.

The switch does nothing to supply voltage until to the single wire going to the right side plug until shifting into neutral.

You sure you have a NO switch and not a NC one?

I am going to have to study this. Some how I must be missing some detail. For the switch I have to be installed like manual says where it says the boat will never start.
Love to be able to talk this thru with you sometime.

 

[alldodge]

Think of it like this, if you had a Bravo drive the connection to the distributor would not be there. No shift interruptor switch and no wire on the plug at all.

This pic shows the 12V connection used to set timing. Note the 2 jumpers, one to bypass switch and one to place ignition module in base timing mode. Motors with a Bravo drive only use the distributor jumper and connect other wire to another 12V source

 

[alldodge]

Remove the 2 jumpers and place motor with just the shift interrupter switch connected. Turn key ON and see if you have 12V on both sides of the switch.

If there is 12V on both sides of the switch, you have the wrong switch

 

[Fun Times]

Serial number is B915133.

0W050471

Possibly to help catch us up on the history of the engine model year vs what switch needed, where did the two serail numbers come about from roughly early 80's to 2005?

Also, what switch part number did you buy? was it a kit to update or just a switch to fit a newer engine model year?

Possibly Mercruiser service Bulletin 2002-1 is at play here fronm the 0B serial number...,

• Shift Components (New Design)
• Shift Components (Old Design)

Or one of the different part numbers used in the 0W serial number,

• Shift Bracket (Sn-0m660000 & Up)
• Shift Bracket (Use With Stamped Steel Rocker Cover)
• Shift Bracket (Use With Stamped Steel Rocker Cover)

https://www.marineengine.com/parts/mercury_marine_parts/sn/0W050471

https://www.bing.com/ck/a?!&&p=177e6607b0d0fa6b59e1d7cbbcf505dc5a779231b8589d93f3645546220dff5aJmltdHM9MTc2ODA4OTYwMA&ptn=3&ver=2&hsh=4&fclid=0c918125-f697-6436-0bd1-9427f705656a&psq=merruiser+Bulletin+2002-1&u=a1aHR0cHM6Ly93d3cubWVyY3J1aXNlcnBhcnRzLmNvbS9BdHRhY2htZW50L0Rvd25sb2FkRmlsZT9kb3dubG9hZElkPTE4Nw