1977 Mercury 500 Thunderbolt 50HP engine harness and wiring harness rebuild

mfh6980

Cadet
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Jul 6, 2010
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21
My wiring harness is shot. While trying to test for a shot in the key switch insulation was falling apart as well as the wires just breaking. I cut everything loose from the key switch which tested fine but looks like it is 30 years old (which it is) so I will replace it with a new push to choke key switch. I started cutting back the wiring harness to find good wire but I don?t think there is any. Just wire skeletons/remains. The harness is $230 (http://www.iboats.com/Wiring-Harness...view_id.174724) I previously rebuilt the engine side wiring harness and at that time considered just building it all from scratch getting rid of the engine and the wiring harness. Any gotchas to doing that? Looks straight forward. Just home runs for each wire to the switch as follows per the attached diagram.

Red ? Solenoid to key position A
Black ? Solenoid to key position D
Orange ? Switch box to key position E
Yellow ? Solenoid to key position B
White ? switched power from key position F used by the choke and other keyed accessories
Gray ? Choke Solenoid to whatever that is on the new push to choke key switch
Brown ? unused as I don?t have a tachometer

Thanks

Mike
 

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