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  1. #1

    Polaris '95 SLX 780 - MFD Temp Gauge Specs

    Hi there,

    I have problems with my MFD. I know its quite common. I have done all the electrical checks and im pretty sure the MFD is out.

    I was just wondering if anyone knew whether the temperature light is just a switch or is the a sender unit located anywhere?

    Im not fussed about any of the guages other than temperature so i would like to just hook up a light to the temperature wire that go into the MFD.

    Just wanting to know whether it is just a switch that i can bypass from the MFD of if it needs to be syncronized etc.

    Any help would be great....


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk

    The temp sender is a thermally sensitive switch. Look for a single Tan wire running from the temp sensor into the electrical box.

    The very early Polaris PWC models did not have an MFD, just a buzzer that sounded when the sender detected over-heat.

    The sensor grounds the Tan wire to the engine block when overheat occurs. The MFD then lights the red LED, and flashes a HOT message on the display.

  3. #3
    Thanks for that.

    Im actually trying to work out whether it is a 95 or 96 model. The specs seem to make mind sound like a hybrid between the two and cant work out, but i understand they both have the same 8 pin mfd.
    Do you think if I just bypass this Tan wire from the mfd back to ground with another bulb in line will it still light when it is overheating or is there some other kind of process beyond me that wont allow this to work??

    Thanks K447.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by jjjhandel View Post
    ...Im actually trying to work out whether it is a 95 or 96 model. The specs seem to make mind sound like a hybrid between the two and cant work out, but i understand they both have the same 8 pin mfd.

    Do you think if I just bypass this Tan wire from the mfd back to ground with another bulb in line will it still light when it is overheating or is there some other kind of process beyond me that wont allow this to work?
    Check the last 2 digits of the HIN number plate on the rear deck. That is the model year.

    The temp sender grounds the Tan wire when over heat occurs. To light a lamp, the lamp would be connected between the Tan wire and 12 volt power.

    I would suggest using a bright LED rather than an incandescent bulb, simply to reduce the amount of current flowing through the sender contacts. I don't know how much power the sender can handle, so an LED is the safer choice.

    Also, a regular bulb filament can fail from vibration, and you wouldn't know the bulb had failed. A LED is much tougher, especially if you can seal it or find a marine grade LED.

    If you connect the LED between the power (Red/Purple) and Tan wires of the MFD connector, then the MFD fuse inside the electrical box can be used to prevent an accidental short circuit from frying the electrical system.

    If you connect the lamp to power from somewhere else, be sure to include a fuse in-line with the lamp.

    Another option is to install a warning buzzer from an early year Polaris. They were used for exactly what you want to do, warn of overheat. If you can find one used, it will not be expensive.

  5. #5
    casey67's Avatar
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    Is your PWC overheating ? Or are you trying to install a overheat warning light ?

    As K447 mentioned,the temp sender is just a switch ( at a certain temp-it switches to ground-sends a ground signal to the MFD when overheating ) if that wire gets grounded-shorted against other metal parts-it will say it is overheating

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    I forgot to mention that you can find a lot of MFD related info here;
    Multi-Function Display (MFD)

    Also, if you want a connector to plug directly into the MFD harness socket, it will be a Deutsch connector. Then you can wire your LED indicator or warning buzzer into the appropriate pins on the Deutsch plug, and have a clean and reversible installation.

    For a 12-pin MFD harness, the mating connector is Deutsch DT04-12P

    For an 8-pin MFD harness, the mating connector is Deutsch DT04-08P

  7. #7
    FLjoyrider's Avatar
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    Or, if you wanted to get rid of the temp sensor alltogether but still know when its getting hot.. you could install pissers.

  8. #8
    I have thought about getting a new harness.
    I thought i might do the same with the fuel gauge. I know the send unit is working. I did a resistence check and it seems fairly accurate.
    I know i can connect a warning light up from the pink wire but if i connect an anolog fuel gauge, does that need to go the same line.
    They are just a resistence meter as i understand but is there an additional wire i would need to run into it?

  9. #9
    Well i dont think it is. The MFD hasnt worked since ive owned it but i would like to hook one up before i have to find out the hard way.
    Do you know if the rev limiter still runs without the MFD hooked up?? I understood it ran seperately from the CDI unit.

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    There are two RPM limiters.

    The CDI has a hard maximum RPM limit, which will be something over 6,000RPM (varies depending on the engine and model/year).

    The other limiter engages when the engine overheats, or runs low on fuel/oil (the exact conditions varies by model/year).

    The overheat limit is directly triggered by the temp sender and sent to the CDI via the Tan (or gray wire on some models), and the MFD just reports the same signal using its red LED and HOT warning message.

    The Low fuel/oil limiter is signaled by the MFD itself, and sent to the CDI using the same Tan or Gray wire as the overheat. If the MFD is not working or is removed, then there will be no RPM limit for anything other than overheat.

    The fuel and oil senders are just variable resistance units; 33 ohms indicates full, 240 ohms indicates empty. This is a standard for the marine industry, and you can probably use another brand of marine fuel gauge with the Polaris sender.

    Polaris' own analog fuel gauge required a special low voltage LR module (2.5 volts, if memory serves). The reason for the low voltage is to ensure that there can never be a spark inside the fuel tank, even if the sender in the tank failed badly. 2.5 volts is just too little voltage to create a spark that could ignite gasoline fumes.

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