64' Merc 850 Tower ignition

Chinpoker

Seaman
Joined
Oct 16, 2012
Messages
72
Ok I've decided to change out the old 50yr old switch which was giving me problems off n on last season and stopped working this year!! What I'm using as a replacement is a Sierra MP39090 which has 6pole connections (B)attery (I)gnition (S)tarter (C)hoke (M)agneto (M)agneto Here's what I've found out I've got 5 wires (Black) - my ground (Red) + what should be 12v but only reading .5volt on the multimeter??? (Pink off whitish) ???guessing ignition ?? But it's live 12.4volt ??? (Orange) starter solenoid touch to red I get nothing touch to the pink/off white turns over the motor (Green) would be my choke but I've rewired that and capped it as the wiring and the choke button stopped working too !! All wires are solid colour! So this is what I've done red wire which should be batt but only has under 1V not sure why yet but hooked up to the B terminal on the switch. Choke wire to term C. Orange to S. Pink/whitish to I. But has the 12V's ( I'm thinking that I should swap the Red wire which is on the B term ?!) any ideas?? Black ground where should that go? on 1of the 2 M terminal?? Which one not sure which of the 2 is the neg terminal?? If I wanted to get a tach signal is I possible to get that from any of those terminal ? I've only got those 5 wires coming from the wiring harness. No magneto got distributor and no switch box! Any insight to what I should try and do I don't wanna fry anything as I can't spend anymore moolah on this project already had to replace 1 hydraulic cylinder N replaced lower unit with a modified 70's unit got a 2.3 gear ratio instead of a 2.1 thanks to the help from "emckelvy thank again" Sorry about the amount of reading just want to give all the info that I know as of now! Thanks in advance on any help!! Dave
 

Chinpoker

Seaman
Joined
Oct 16, 2012
Messages
72
No Title

Red - .88volts Off white - 12.89volts Orange - 0 volts Blue - 0volts but not in use Black ground
 

Chinpoker

Seaman
Joined
Oct 16, 2012
Messages
72
Ok another question if I wired the wires to the wrong terminals on the ignition switch could that cause me to not have any spark but cranks??
 
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