Installing Trim guage on Yamaha

Discussion in 'Bubba's Outboards' started by Grumper, Apr 15, 2007.

  1. Grumper

    Grumper New Member

    Messages:
    2,277
    State:
    Crystal City MO
    I installed a trim guage on my boat, and I can't get it to work. The motor is a '04 Yamaha 70. I know I have the guage wired correctly, but It still won't work. When I hook up the pink wire to the S terminal on the guage, the needle bottoms out way above the up position. The manual says when this happens there is a bad sending unit, or no continuity. The sending unit has never been hooked up, and I checked it with an ohm meter. I get resistance when I check the pink wire off the sender to my ground on my tester, and black to red on my tester. and nothing when I check pink to red, and black to black. There are no other guages on the boat, and I have found a wiring harness coming out of the control box, so I am assuming that these wires are for the guages? I have my guage hooked to the pink wire coming out of this harness. Any ideas?
     
  2. Bobpaul

    Bobpaul New Member

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    3,039
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    Supply NC
    Let me check the wiring on one I have at the shop now. I'll get back with you soon.

    I know that key on power comes from the yellow wire in Yamaha's at the control box, if that's any help.
     

  3. Bobpaul

    Bobpaul New Member

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    You should get a variance in voltage from the pink wire when tested at the gauge, as the motor is trimmed up and down. If you don't, I'd suspect the sending unit.

    See if you get a variance in ohms through the pink and black as the motor is trimmed up and down.
     
  4. Grumper

    Grumper New Member

    Messages:
    2,277
    State:
    Crystal City MO
    I tested everything again, and I am getting a good ohm reading at the sending unit, It goes up to about 170 ohms at raise, and down to about 15 Ohms at lower. The problem I am having now, is when the wires go into the motor housing, they sorta dissapear into the wire harness. I thought the pink wire coming out of the control box was the right wire, but it is constant 12V. I tried hooking up all of the other wires, but they won't work either. The sending unit has a black and pink wire, and I thought about just cutting them there, and spicing the guage in, but I hate to do that to that new of a motor. I figure that it has to have a hookup somewhere, if it has a sending unit. The boat has no other guages in it, and it has got me stumped.
     
  5. Bobpaul

    Bobpaul New Member

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    3,039
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    Well, you just need a color coded wiring diagram.

    The trim gauge wires do connect up to the harness at the engine. I'll look into the color code at the console.
     
  6. KGK20

    KGK20 New Member

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    101
    State:
    MISSOURI
    it would help if gary wasnt color blind
     
  7. JAYNC

    JAYNC New Member

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    1,312
    State:
    Newport N.C.
    Go to www.seloconline.com and pay for an online manual subscription for your engine. Its only $30 for 3 years and they update things all the time. I actually looked at my diagram to help you out, but mine is a 75hp four stroke mercury and the harness is different than the 2 stroke engine. The manual will save you a lot of headaches and save you from hacking a new wire harness. Mine has wires with connectors already installed and tied back for accessories, not sure if yours does or not.