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Tilt and trim guage 1989 Merc 75 hp Wiring and signal

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  • Tilt and trim guage 1989 Merc 75 hp Wiring and signal

    Picked up a used 75 hp

    1. any clue where the tilt trim position rocker switch is located
    2. How many wires?
    3. How to connect wires to the trim dashpanel gauge?
    4. Are tilt trim gauges universal? Evinrude swapout for a Mercury gauge?

    any tips appreciated winter here in syracuse boat is tarped for the winter

  • #2
    Well, it doesn't look like Mercury made a 75HP motor in 1989. It is either 70HP or 80HP.

    They do show a trim sender for the 70HP motor. It is on the transom clamp. It should be 2 wires, ground and sender. The sender wire would connect to the gauge.

    Not sure if the J/E gauge will swap with Merc. Doesn't hurt to try it, if you have the gauge.

    Not sure if your wiring harness already has a wire for trim sender.. If not you will need to pull one.


    • #3
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      I just picked up a 2002 115 2 stroker with a trim position sensor. Do you know how the signal is generated and what changes the reading?

      I assume there is a Rheostat with the movable arm connected to the engine and the rest connected to the clamp bracket. Changing resistance changes the current and thus the position of the needle in the dash monitor. In asking the question I am curious as to calibration. Since different boats have different transom angles, if one wants a certain mark on the meter to represent a desired trim position it would be nice to calibrate it.

      Also, just a side note of interest is how is that made waterproof considering the tilt range of the engine to clamp bracket interface.

      If you are new to boating or have a new boat, a knowledgeable friend could show you how to operate your boat and save you a lot of grief, maybe some money, and maybe your life.