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  1. #1
    Seaman Apprentice
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    Feb 2010
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    Default Is there a trim sensor?

    I have a '90 Chaparral w/ 305 Mercruiser. It has a trim gauge that says down but you have to trim further to go all the way down, then the gauge jumps to up. I usually just gauge where im trimmed by ear. You hear it go under pressure when ur all the way down. But for some reason w/ this one it never binds and makes that noise. It seems to go down then come backup. Its hard to find that sweet spot that way. Is there a sensor or something I can replace?
    1990 Chaparral 2000 SL 5.0L v8

  2. #2
    Rear Admiral
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    Default Re: Is there a trim sensor?

    got to "Adults only" sticky, #9, download Mercruiser Alpha 1 manual #6. Section 4A tells you all about the sensor and limit switch. If you have the "old style" (wire wound resistor/wiper) switch you may be able to disassemble it and clean it up to get it to work. The "new style" switch is not serviceable. Replacing the switch is easy, however running the wires through the transom is a MAJOR PITA. The old wires will not fit the new switch. Cutting and splicing the wires is one possibility, but is NOT recommended.
    Terry
    87, 4WINNS H 190
    470/Alpha I

  3. #3
    Captain
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    Central CAL
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    Default Re: Is there a trim sensor?

    Sounds like it may just be out of adjustment.
    When will people learn that impellers require regular
    replacement and are not drive it till it pukes items?

    1984 Regal Medallion 195
    3.8 V-6 with the dreaded
    OMC Stringer Drive.
    2003 Avalanche w/Hypertech

    If it ain't fixable - don't break it!

  4. #4
    Ensign havasuboatman's Avatar
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    Lake Havasu City, AZ.
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    Default Re: Is there a trim sensor?

    There are two "sensors" One is called the trim sending unit. The other is the trim limit switch. They are on the transom assembly mounted over the drive piviot pins. The sending unit (says that right on it) is the one that activates the gauge.
    Hey, it was like that when I got here.

  5. #5
    Seaman Apprentice
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    Default Re: Is there a trim sensor?

    Port side, trim limit, is not even connected. wires were cut and the sensor itself looks shot. will try to clean and wire it up but where can i find this part if need be? didnt see it on iboats.
    1990 Chaparral 2000 SL 5.0L v8

  6. #6
    Seaman Apprentice
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    Default Re: Is there a trim sensor?

    update: cleaned trim limiter and rewired to existing wires i found connected to each other tucked right inside. when the limiter is connected it trims down but wont come back up. when i disconnect the trim limiter and connect the wires to themselves, it works fine. this tells me the limiter is bad but after cleaning it up i dont see how it could be bad. not much to it. connections are good. may just have to find a new one and try that. otherwise possibly wiring is wrong up top somewhere.... thoughts?
    1990 Chaparral 2000 SL 5.0L v8

  7. #7
    Chief Petty Officer
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    Mar 2010
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    Charlotte, NC
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    455

    Default Re: Is there a trim sensor?

    I am in the same situation and the answer is to test it. Try it first at the wires inside the boat, pop the top off the limiter and jumper it there and see if you get resistance at the wires inside (voltmeter looking at ohms for continuity). Vice versus, jumper the wires inside and check for continuity at the switch.

    There's not much to wire wrong, it is two wires, and you are right I don't really see wha tcould be going wrong with it but the trailer button works so I am using that for now, but I will fix it...

  8. #8

    Default Re: Is there a trim sensor?

    For you to have the trim system working correctly, You will want to order and install a new switch & sender kit.

    Mercruiser part number (805320A 1) Includes both trim limit switch & sender.
    805320A03 SINGLE STATION SENDER KIT (BLACK) 805320A1 $99.92 $94.10.
    This information is near the bottom of the part numbers in the link below, But for a photo of the item see number 12 in this link. Good luck with it.

    http://www.mercruiserparts.com/Show_...STEERING+LEVER

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