Shift Interrupt Switch Connection

[ahaling]

Shift Interrupt question: I have a two wire shift interrupt on my 1995 4.3 mercruiser. Replaced carbureted engine that had TB-IV with newer 2007 MPFI engine.

Where do I connect the white/green stripe wire from my shift interrupt switch now that my analog system is gone? I know on the TB-IV it connected to the distributor and then to the TB-IV ignition module via the white/green stripe wire and white/red stripe wire.

I’ve read it may go to the Negative gray wire on the coil. Coil has gray and purple wires with Molex connector not terminals so I would need to splice into the gray wire. I’ve also read the newer system may need a 12v power from purple wire to the white/green stripe wire then what was ground go to one of the distributor wires. However, the Distributor only has one connector with three wires, red, black and yellow. It appears newer then the Delco EST type that has two connectors and 5 wires. Thanks.

 

[Bt Doctur]

you might have to wire the 2 wire in series with the coil power wire instead of a ground type

 

[ahaling]

I thought about that. I guess I'll research that further and see if I have a NO or NC switch. Wouldn't work this way if NO. Also, I'm wondering how much voltage this switch can take as it was used to ground the original circuit and not pass constant voltage.

 

[Chris1956]

Get a wiring diagram from each engine and compare the wiring to the switch. You can then verify what kind of switch you have.

I would expect both motors to have a CDI type ignition, but am not sure of the exact wiring.

 

[ahaling]

Do you have a resource for the wiring diagrams? I've looked for hours and can't find one for my later model engine.

 

[Chris1956]

A service manual for the newer engine should have one. You probably want one of those anyway, as they are real handy when something like the ignition breaks.

 

[ahaling]

2007 4.3 L with MEFI4. Do you have a resource?