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    Topic
  • #49058

    Blair Ostergren
    Participant
    Vessel Name: Riley Blair II
    Engines: 4bt
    Location: Richmond, VA
    Country: US

    I have an alarm going off with Good temp and oil pressure. I disconnected the oil pressure switch and alarm does not sound. I have ordered the SMX switch from SBMAR. My question is how should I install the SMX Switch. It has a single pole. The switch I am removing has a clip and two wires going to it. I believe it is cummins part 3056344. Do I attach both wires to the single SMX pole or does one need to go to a short ground?

    Thx
    Cpt.Blair

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  • #49089

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    No, do not attach both wires together. A single terminal switch is engine ground, aka case ground, with the one wire being a signal wire. A twin terminal switch is a floating ground which is a signal wire and a ground wire. Are you sure what you are replacing is a “switch” and not a “sending unit” ? Big difference. The Cummins OEM instrument cluster setup does not include a switch, just the sending unit and it is the PCB at the instrument panel that decides when to sound the alarm. Of course things could be “builder specific” as in Bayliner installs or a prior owner did his own thing.

    #49084

    Corey Schmidt
    Forum Moderator
    Vessel Name: Rebel Belle
    Engines: Cummins
    Location: Oxnard, CA
    Country: USA

    Case ground

    A single pole simple low oil pressure switch will ground itself to the engine case so only one wire is required to be run to the panel / lamp/ buzzer circuit. When the switch is working, it will sound when the IGN is on and the engine is not running, then stop alarming after the engine is started and has good oil pressure.

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