Help adding kill switch to a '77 Mercury Tower of Power

[bsutravis]

I'm dealing with a '77 Mercury 1150 / 115HP - Ser. Num 4569747​

Need some help here... I'm leaving to fish Norfork and Bull Shoals down in Arkansas in a few weeks. Since it's been 5-6 years since I've had my boat down there from my home in Indiana I thought I would check the Arkansas regs to make sure there wasn't anything new that I needed to know about.... well there was. Arkansas now has a law requiring a kill switch.

Can anyone help point me in the correct direction on adding a kill switch? I assume I can attach the switch onto my dashboard, but I'm not sure what wiring harness wire(s) I need to splice into to make it all work. I see some kill switches that have 2 terminals and some that have 4. With the older distributor style Merc I'm not sure how to begin wiring this in so that I'm safe and legal!

Thanks for any help!

Travis

 

[Chris1956]

If your wiring harnesses are original, you will need to interrupt the power on the white wire, coming from the key to the white terminal, next to the red terminal on the switchbox.

If you have the original MerControl, I guess the simplest way would be to take it apart, and splice the switch into the white wire. The switch would need to open to kill the ignition. If you have the room on the control and can find a switch that fits (probably unlikely) mounting the switch on the MerControl would be the cleanest.


Alternatively, there is another was to kill spark. If you look on the motor for the blue mercury switch and trace it to the switchbox brown terminal. That kills the ign when the motor kicks up. You could run a wire to the dash and ground it with a dash mounted safety kill switch.

 

[bsutravis]

Thanks for the fast reply Chris... yes all the wiring is original, and no there is certainly not any room inside the MerControl to retrofit a switch. Could I mount the kill switch on my dash, cut the white wire before it enters the MerControl and simply add wire up to both sides of the kill switch?

 

[Faztbullet]

The correct way is to ground trigger out...….Mercury installation instructions with their kit stated not to break ignition wires.

 

[bsutravis]

Sorry.... how do you ground out the trigger?

 

[Chris1956]

See my third paragraph, duplicated below, to ground out the trigger.

Alternatively, there is another was to kill spark. If you look on the motor for the blue mercury switch and trace it to the switchbox brown terminal. That kills the ign when the motor kicks up. You could run a wire to the dash and ground it with a dash mounted safety kill switch.

 

[bsutravis]

OK, just so I'm clear... I want to run a ground wire from one pole on the kill switch from my dash, back to where my mercury switch connects to my switch box. I then want to find a ground behind my dash and ground from there to the other side of the kill switch? So I only need a kill switch with 2 terminals coming out the back, not 4 like I've seen also.

Sorry to be so paranoid, I just want to make sure I'm not going to screw this up somehow.

Thanks!

 

[Chris1956]

Yes, find a ground on the dashboard and connect a kill switch that "Makes", when tripped. Connect the other end to the brown terminal on the switchbox, as pictured in your post.

Remember that when the kill switch is tripped, the ign is still on, so turn it off as you do now.

 

[bsutravis]

Great... thanks for all the help. I've got a switch ordered so I'll get it installed in a few days. Much appreciated.