1978 ? mercury 500 thunderbolt wiering

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  • June 18, 2020 at 12:14 am #206042
    Anonymous

      i think i have a 1978 mercury 50 hp 500 thunderbolt ignition and i am rewireing a harness to a key switch i found this diagram online and it matches my wires except it has tan and i have a orange wire im guessing thats the tan i cant seem to see what the white wire does can any one explain what each wire goes to and where to put it for start ext thanks ikn advance

      June 18, 2020 at 4:46 am #206048
      frankr
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        White wire supplies 12V to the choke switch and tach when key is “on”. It is not used by the motor itself, thus no connection at the plug.

        June 18, 2020 at 8:30 am #206052
        dave-bernard
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          US Member

          Frank is correct
          yellow is start solenoid
          gray is choke solenoid.
          black is ground
          red is positive.

          June 18, 2020 at 12:04 pm #206085
          Anonymous

            what year would this be being a serial # 4078181

            June 18, 2020 at 3:21 pm #206096
            dave-bernard
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              US Member

              1974.

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