Can I convert a 5 terminal ignition switch to a 3 terminal ignition switch on the dash.

[Freeridr22]

Hello I have a 1979 mark twain trihull with a 90 hp mercury 2 cycle ADI 6 cylinder. The original wiring in the throttle control is trash. Also the 5 terminal ignition switch marked A B S M M is broke off. I am changing the wiring in most of the boat as it is not safe. I rebuilt the mercury throttle and I am happy with not needing to replace it. However, it does not have a laynard kill switch and I want to add one to the dash. Also I want to move the ignition switch to the dash as well since I have changed the seats. The problem arose when I obtained a new ignition switch. It is a Sea dog Line 420365-1 Three position ignition switch. This clearly hasonly the Battery Solenoid and Ignition. I am aware of the Ms on the other as meaning magneto and have read much on this topic but I am very new to the boating world and only have diagrams, youtube, and forums to combine with my automotive knowledge. Finally, my question. Can I use this ignition switch, on the dash, by connecting the correct wires from the old ignition switch, and connect the two Ms to a laynard killswitch. Or is this switch completely incorrect for what I am wanting to do and have to order another switch with the 5 terminals. Thank you for any insight you maybe able to offer me.

 

[Freeridr22]

Hello I have a 1979 mark twain trihull with a 90 hp mercury 2 cycle ADI 6 cylinder. The original wiring in the throttle control is trash. Also the 5 terminal ignition switch marked A B S M M is broke off. I am changing the wiring in most of the boat as it is not safe. I rebuilt the mercury throttle and I am happy with not needing to replace it. However, it does not have a laynard kill switch and I want to add one to the dash. Also I want to move the ignition switch to the dash as well since I have changed the seats. The problem arose when I obtained a new ignition switch. It is a Sea dog Line 420365-1 Three position ignition switch. This clearly hasonly the Battery Solenoid and Ignition. I am aware of the Ms on the other as meaning magneto and have read much on this topic but I am very new to the boating world and only have diagrams, youtube, and forums to combine with my automotive knowledge. Finally, my question. Can I use this ignition switch, on the dash, by connecting the correct wires from the old ignition switch, and connect the two Ms to a laynard killswitch. Or is this switch completely incorrect for what I am wanting to do and have to order another switch with the 5 terminals. Thank you for any insight you maybe able to offer me.View attachment 327543View attachment 327544View attachment 327545View attachment 327546View attachment 327545View attachment 327544View attachment 327543View attachment 327544View attachment 327545View attachment 327546

Sorry for picture repeats

 

[Chris1956]

Modern Outboards need the 5 terminal ignition switch. They run on an ADI system, where grounding the "M" wires kills the ignition. They also need an electric choke function.

 

[Freeridr22]

I have an electric choke set up and preintregrated mercury trim. I looked at universal laynard killswitches and they have the two Ms on them and since grounding out it what kills the engine, could I not run the m wires to the killswitch without running the to the ignition?

 

[Chris1956]

I have an electric choke set up and preintregrated mercury trim. I looked at universal laynard killswitches and they have the two Ms on them and since grounding out it what kills the engine, could I not run the m wires to the killswitch without running the to the ignition?
[/QUOTE]

I suppose you could, and use the kill lanyard each time you want to stop the motor. You will also need to turn off the key switch to avoid draining your battery. So to start the motor, plug in the lanyard and turn the key. Now drive the boat. When you stop, pull the lanyard and turn the keyswitch off. Don't forget the ign key and the lanyard at home, as you go nowhere without both. You also get to split open the wiring harness to pull the ground and killer wire to the killswitch and lanyard.
That is very inconvenient, IMO. Why exactly do you want to do that to avoid buying a $15 ignition keyswitch w/ built in kill lanyard? I suppose you could look at it as your answer to Rube Goldberg.

 

[Freeridr22]

Thank you so much for helping me with this. You dont know how long I have mulled over this giving me a head ache. I see your point as to why it would work but would be inconvienant. I am redoing the entire electric in the boat because it set outside for decades without a cover as well as it is missing many safety componets such as fuse box, killswitch, battery shut off switch. I want to move the ignition switch from where it was in the throttle to the dash and and the kill switch and fuse box. I had this one i got for free and wanted to try and make it work but I now see the folly in this. I guees ill have to get the 5 terminal and run the wires through the fuse box, then the ignition switch, killswitch, and back down to the throttle, (since the choke, tilt and trim are in there.) Bummer. Allwell I got all winter. Lol.

 

[Chris1956]

Normally the motor harness connects directly to the ign keyswitch. An inline fuse is installed on the battery wire at the motor, to protect the engine. This keeps the wiring simpler and less prone to failure due to corrosion or wiring component failure.

I am not sure what year Merc you have, so I do not know if you have a fuse on the motor. Early models did not.

 

[Chris1956]

Normally the motor harness connects directly to the ign keyswitch. An inline fuse is installed on the battery wire at the motor, to protect the engine. This keeps the wiring simpler and less prone to failure due to corrosion or wiring component failure.

I am not sure what year Merc you have, so I do not know if you have a fuse on the motor. Early models did not.

You will also need to wire the power to the starter solenoid thru the neutral safety switch, located in the control.