Mercury 850 thunderbolt ignition switch wiring

[Hotrod758]

I have a mercury 850 serial 4233250
I changed the shifter control box to a new style without the ignition switch so I want to wore a new ignition switch to the the steering wheel console new switch has the letters S M B M I C on the back of switch which wires would go where I was trying to figure it out from looking up a diagram and rhe original switch is lettered differently so I'm just not sure has anyone done this ? Any help would be much appreciated I'll post a picture of the back of the new plug im trying to wire up

 

[dwco5051]

Don't know if this helps. Your SN indicates distributer ignition. You are still going to have wire through your control box for the neutral safety start switch.

 

[merc850]

B is + battery, I is white wire, S is yellow, C is gray. M is not used for your ignition.

 

[Hotrod758]

B is + battery, I is white wire, S is yellow, C is gray. M is not used for your ignition.

So would the black wire possibly go to m one m is a magneto that would be obsolete I assume and the other m Is a kill key off so would the ground go to that ?

 

[Hotrod758]

B is + battery, I is white wire, S is yellow, C is gray. M is not used for your ignition.

And the tan wire "E" goes down the wire harness but don't attach to engine wire harness which is weird so I'm assuming that would be kinda a universal plug there's probably another engine that uses the tan wire so I can just cut that it's unused correct ? Sorry not trying to sound dumb just the wiring part confuses me

 

[merc850]

And the tan wire "E" goes down the wire harness but don't attach to engine wire harness which is weird so I'm assuming that would be kinda a universal plug there's probably another engine that uses the tan wire so I can just cut that it's unused correct ? Sorry not trying to sound dumb just the wiring part confuses me

The E wire is orange and was used in older models for ignition you don't need it.

 

[Hotrod758]

The E wire is orange and was used in older models for ignition you don't need it.

So where would black go and where would the 2 kill wires go? Would they go to the 2 ms?

 

[merc850]

So where would black go and where would the 2 kill wires go? Would they go to the 2 ms?

The kill wires don't apply - in this case the motor is stopped by cutting power to the white wire, the black wire is for the tach ground at the plug for the tach.

 

[Hotrod758]

The kill wires don't apply - in this case the motor is stopped by cutting power to the white wire, the black wire is for the tach ground at the plug for the tach.

So the black wire don't go to the switch and the kill switch I can wire it inline with the white to kill that power when lanyard pulled? Leave the two m terminals empty ?

 

[merc850]

Don't wire a ground to the white terminal it is + when engine is running!
You need a kill switch that opens when pulled, a switch that closes when pulled can be wired to the mercury switch side of the switchbox.

 

[Hotrod758]

Don't wire a ground to the white terminal it is + when engine is running!
You need a kill switch that opens when pulled, a switch that closes when pulled can be wired to the mercury switch side of the switchbox.

What do you mean the mercury switch side ?

 

[merc850]

What do you mean the mercury switch side ?

The brown terminal on the distributor (3 terminal side) of the switchbox.