Jinma 254 Ammeter wiring

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    • July 17, 2026 at 4:15 pm #50501
      DemocracyNow
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        While replacing my Jinma 254 ammeter with a voltmeter the wiring has confused me.
        Both Green wire from the 25 amp fuse holder wire to the Ammeter and Yellow wire from Key-switch to ammeter are 12 volts hot. I can remove the yellow wire from the ammeter and the tractor will still start and all instruments will operate, except the ammeter .

        I thought the green wire from the 25amp fuse holder fed 12volts/ current through the ammeter and then fed the key switch 12 volts which powered the solenoid then starter.

        Can anyone clarify my thoughts?

      • July 17, 2026 at 4:35 pm #50502
        DemocracyNow
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          Ps;I can remove both the green and yellow wires from the ammeter and measure 12 volts hot from the green wire and separately from the yellow wire coming from the key-switch. As it was the ammeter was without polarity and was fed 12 volts from both wires.

        • July 17, 2026 at 11:10 pm #50503
          Piper184
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            That is correct. With the key on, both wires are connected to the positive side of things, just from different points. One at the battery cable on the starter and the other through the alternator. This way the meter can “read” the flow of current either into the battery from the alternator, or out of the battery to other circuits through the key switch.

            See attached diagram. Wire numbers may be different on your tractor, but the circuits are all basically the same.

            A volt meter should be wired to the hot side of the switch with the key on to the + terminal and to ground on the – terminal.

             

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          • July 18, 2026 at 6:35 am #50505
            DavidPrivett
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              I converted mine to a volt gauge also I just put the two wires together and also used it for my hot for the voltmeter from that same connection. just come up with a good ground and a switched hot from the headlight circuit if you want the light in the gauge to work when dark.

              • July 18, 2026 at 8:09 am #50506
                DemocracyNow
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                  David , Thanks for the response.
                  I will do the same process as you did and I will choose the #3 green wire coming from my fuse holder and 25 amp fuse,swapped out for a 2 amp to protect the voltmeter.
                  But the yellow # 5 circuit wire from the OEM ammeter is a hot wire and cannot be used as a ground, so another ground must be found.

                  My confusion with ammeter wiring was erased after I researched ammeter nomenclature.
                  Ammeters at first thought appear to flow and show current  flow without the need for a grounding potential.
                  The axiom for ammeter installation says always place the ammeter in circuit between the battery +and alternator/ generator/load (lights, alternator exciter ,ect)+ circuit  and electrical energy then either  flows to the battery or to the alternator/generator/load(lights, alternator exciter ,turn signals ect. )

                  I suddenly realized that there is a negative electrical potential for ammeters and that as electricity is being generated at the alternator/generator  it is flowing through the ammeter towards the battery + wiring towards the battery negative ground.
                  As the battery is being depleted that electrical energy is flowing backwards through the ammeter towards the starter/alternator ,lights grounding points.
                  So Ammeters are connected to positive wiring and measure the push/ pull of electricity and that electricity is eventually going to grounding points either at the battery or load.

              • July 19, 2026 at 6:42 am #50513
                DavidPrivett
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                  yes all you wrote is true , you did your research well. Alot of amp meters are not sensitive enough to display much of anything one way or another after start up, that is why I prefer voltmeters.

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