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Issue with Voltmeter on dash reading low

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  • Issue with Voltmeter on dash reading low

    Been having an issue with my voltmeter gauge. It generally reads about 12-13v depending on RPM. I assumed the alternator was dying and even started looking into grabbing a new one. But before ordering, I put my hand held voltmeter on the back of the alternator and she is charging at 14.2v...just like it should. And when I go into my Garmin GPS...it is showing 14.2 as well. Seems like the GPS runs almost exactly 1v higher than the gauge reads. Gauge running 13...gps shows 14....and it obviously moves based on RPM's, but seems to follow that 1 v off measurement. Not sure what could be causing this. Thinking either bad gauge or somehow there is resistance in the wire to the gauge...but not sure how that would have happened. Thoughts?
    2004 Maxum 1800SR3 w/ 2010 Mercruiser 3.0 Alpha 1 Gen 2

  • #2
    You're putting way too much thought into it....

    All gauges go out of calibration from time to time for a variety of issues....either live with it or buy a new one and be done with it


    • #3
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      Check the connections to the voltmeter for corrosion/tightness. Resistance (electrical) at those connections can cause the difference. And gauges, gps, and handheld voltmeters can all have varying degrees of accuracy with the helm mounted gauge probably the least accurate of the bunch. All gauges, regardless what they measure, should be considered as providing "relative" readings. If any gauge reads abnormal, that's the key to break out the accurate test equipment and begin verification that there is or is not an actual problem.