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1970 Johnson 25hp starter wiring

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  • 1970 Johnson 25hp starter wiring

    I have a 25hp Johnson model 25R70E I purchased last summer. It was at one time set up for electric start. When I purchased it, the starter was gone, but the bracket and solonoid are still there. There are two wires hanging down from under the flywheel that are terminated with plastic clip connectors (not sure what they are for). The wires to/from the solonoid had all been cut. The battery cables had all been removed. There was no push button for starting and no cut off switch (both had been removed). My plan is to buy an aftermarket starter, starter switch and a cut off switch on ebay. I just don't want to make those purchases, until I'm sure about what I'm doing. Is there anyone with a diagram of how to wire it all up, from the battery all the way to the starter, especially around the solonoid, and kindly suggest what gauge of wires I should use for each part. Thanks.

  • #2
    Re: 1970 Johnson 25hp starter wiring

    This is not the exact diagram for your motor, but it should give you an idea.
    Attached Files


    • #3
      Re: 1970 Johnson 25hp starter wiring

      4 ga for the battery cable and 14 ga wire for everything else should work fine.
      '77 Crestliner Voyager Deluxe 16' (semi V), Spartan WondeRoll tilt trailer, '81 Johnson 25 hp, '88 Johnson 30 hp, '87 Evinrude 30 hp


      • #4
        Re: 1970 Johnson 25hp starter wiring

        Thanks so much.


        • #5
          Re: 1970 Johnson 25hp starter wiring

          The two wires hanging down from under the flywheel are the kill circuit. They can go direct to a pushbutton switch, which when pushed, completes the circuit and kills the motor. The diagram is for a later model motor, but the solenoid circuit is similar. +Battery goes to one side of the solenoid (Large post) and hook up a 14 guage wire to the same post. That 14 guage wire will go directly to one side of the start pushbutton. Then connect another wire to the other side of the pushbutton and run that wire back to the small solenoid terminal next to the large battery terminal. Ground the other small solenoid terminal to the engine block. Then run a 4 guage cable from the other large solenoid terminal to the starter. Then 4 guage ground cable from -battery to starter bracket. Thats it!


          • #6
            Re: 1970 Johnson 25hp starter wiring

            Thank you all for your responses and prefessional help.


            • #7
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              Re: 1970 Johnson 25hp starter wiring

              Ok, I finally got around to hooking all this up. I did it according to the description in the most recent post. When i push the starter button, I hear the relay click, but the starter doesn't do anything. I did some troubleshooting and the starter works when I hook the battery straight to it. So I checked some continuity. Everything is good except it appears that the relay switch has constant continuity (is closed) until I push the push button starter switch (then it opens), and there's no continuity until I release the push button again. Is it possible that the relay switch is shot now or did I wire it wrong? Any further help would be much appreciated. Thanks.