470, 3.7L -Interrupt switch wiring - Old vs New

[nwboater45]

I have an 1989 470, 3.7L, 165 HP Mercruiser. To make a long story short (I have posted the other part of the story earlier) I need help with the interrupt switch wiring. I believe I have a bad connection in the switch which keeps cutting out the engine when shifting. I have attached the new shift panel and old shift panel for reference. The new shift panel has two black wires and the old has a black and white wire with green stripe. I have read in these forums to get rid of the terminal block. But which of the black wires go to the white with green stripe wire? Or does it really matter? I sent this question to wholesale marine who I bought it from but since they don't have a tech they couldn't answer it.

Thanks.




View attachment Existing Shift Panel.pdf
View attachment New Shift Panel.pdf

 

[dccordell]

Re: 470, 3.7L -Interrupt switch wiring - Old vs New

Until the 470 pros make it here, if I remember correctly, the interrupt switch works by simply grounding the (-) terminal on the ignition coil when the shift mechanism is stressed enough coming out of gear.

So, with the new shift plate, one of the wires will go to a ground, and the other would go to the (-) side of the coil. When the switch is activated via shifting action, the coil is momentarily grounded, engine stalls, drive comes out of gear, switch is deactivated, and engine resumes operation.

This is all assuming I'm remembering how I wired mine... it's been over a year since I rewired my boat, so my memory is foggy at best!

 

[Bondo]

Re: 470, 3.7L -Interrupt switch wiring - Old vs New

I have an 1989 470, 3.7L, 165 HP Mercruiser. To make a long story short (I have posted the other part of the story earlier) I need help with the interrupt switch wiring. I believe I have a bad connection in the switch which keeps cutting out the engine when shifting. I have attached the new shift panel and old shift panel for reference. The new shift panel has two black wires and the old has a black and white wire with green stripe. I have read in these forums to get rid of the terminal block. But which of the black wires go to the white with green stripe wire? Or does it really matter? I sent this question to wholesale marine who I bought it from but since they don't have a tech they couldn't answer it.

Thanks.

Ayuh,.... That's the symptom of a Bad Cable, not a bad switch,....

 

[Bt Doctur]

Re: 470, 3.7L -Interrupt switch wiring - Old vs New

" I have read in these forums to get rid of the terminal block. But which of the black wires go to the white with green stripe wire? Or does "

No one would tell you that. It`s needed to have it shift correctly. But being that you have the new type, you need to ground one of the wires and the other wire goes to the neg side of the coil. but considering it`s the lower shift cable causing the problem in the first place
you will still have a stalling problem when shifting.