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  1. #1
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    Don or someone help with trim gauge

    2008 200 Optimax #1B515541.
    My trim gauge is stuck in the up position, doesn't move. I have scoured multiple previous posts about this with none giving a final diagnosis. It is currently stuck in the full up position. When I disconnect the brown/white it stays in the full up position. When I ground the brown/white it goes to full down. Does this indicate bad gauge or bad sending unit? Thanks for the help in afdvance.

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    #2
    Looks like you diagnosed it as a bad sending unit or signal wire issue. Gauge is working according to what you are telling us, in my opinion.

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    #3
    So I need to purchase a sending unit and not a gauge? That is good news as this is on a Triton with the beede combo gauges which are next to impossible to find, thanks.

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Don't buy a sensor just yet. Let's verify how your sensor is WIRED.

    -Verify the Brown w/White stripe wire is run up into the cowling, and connected to the Brown w/white stripe wire at the Oil Pump (right front corner of engine).

    -Verify that the Brown w/white stripe wire is not disconnected at any adapter that may be present for the keyswitch harness (some boats have an adapter from the old-style harness to a 14 pin, such as your engine uses).

    -CHECK THE GROUND STRAP FOR THE MIDSECTION- Port Side, at the Lower Engine Mount NUT. Often cut off due to worn engine support devices (or over-zealous DOWN trim operation once device is put in place). With the original Trim Sensor, this ground was the ONLY ground source to make the sender function (also provides continuous ground to mid so the corrosion control system works as designed).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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    #5
    Don, I did the ground test on the brown/white at the connection inside the cowling where you state above. The gauge went all the way down as mentioned above. So with that test I feel that wire, at least going to the gauge, is good. I visually checked the ground connected to the sensor at the mid section and it appears to be whole, although I didn’t ohm it. I have not checked any other ground strap but will when I get home today. Thanks for the help gentlemen.

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    Likely that lower mount ground strap. The newest version of the analog sensor now has it's own separate ground lead that connects up inside the cowling (so the sensor would work even if the continuity ground strap broke).

    Reeds Injectors
    Last edited by EuropeanAM; 11-27-2019 at 06:16 PM.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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    #7
    I have looked closely and I believe your speculation of "Often cut off due to worn engine support devices (or over-zealous DOWN trim operation once device is put in place)"may be the answer. The sending wire coming off the sensor, not the ground, does not look healthy. It looks like it has been pinched, and possibly broken. It is bent and kinked right at the sensor. I ordered a replacement and hope that fixes the issue, thanks again for the help it is greatly appreciated.

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #8
    Good that you caught that- but the ground I'm referring to is a braided/bare wire, which runs from the lower engine mount NUT to the Swivel Bracket (affixed to the swivel bracket with a 6mm bolt).

    Item# 9 in the below Diagram:

    Attached Images Attached Images


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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    #9
    Ahh, I’ll check that as well, thanks.

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    #10
    To give this some closure to this thread and hopefully help someone else out struggling to find a definite solution as I did (never been accused of being the brightest).

    1) Checked all ground/bond straps per Don - All was good
    2) Did short test at gauge (ground the send terminal) - Gauge moved as it should have
    3) Grounded sending wire in engine cowl - Gauge moved as it should
    4) Replaced with new sending unit - Trim gauge is now fully functional

    As stated hope this helps someone along the way and thanks to the help of Don and Phisherman