Shift Interrupt Switch Problems

[Maxum88]

Hi Guys,

I read Don's post about how the shift interrupt switch works, but my question is, What can I do to test while it's on the trailer? I put a meter to it and figured I would get 12v to one side of the switch and I have nothing. I want to ensure I have everything figured out before I take it out on the water again.

I have an '88 Maxum 3.0L Mercruiser w/ a prealpha outdrive. When it's on the trailer & w the muffs on, I push in the "switch" and the motor doesn't die, which leads me to believe I'm not getting my power...but then again, the switch only works when in the water and the prop is under load.

Thanks!!!

 

[Bt Doctur]

Re: Shift Interrupt Switch Problems

switch will /should stall the motor when operated by hand on a trailer, switch is set to ground the neg side of the coil using a points and cond ign. TBIV has a green/white wire that goes to the stud at the rear of the dist. I think TB V, MPI, EFI all need 12V applied(?)

 

[Maxum88]

Re: Shift Interrupt Switch Problems

Thanks Doc, like I said I'm not getting any voltage to the switch and it isn't stalling the motor when engaged. I'll pick up a book w/ schematics and start troubleshooting!

 

[Don S]

Re: Shift Interrupt Switch Problems

Here is the wiring diagram for your engine (assuming you have points ign. and not the DDIS) The white/green wire is spliced into the gray wire that is attached to the coil. Use your Ohm meter to check the wire, it may be broken
You should be able to activate the switch by hand and kill the engine.
You can also disconnect the shift interrupt switch and check it with an ohm meter to make sure it works.