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  1. #1

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    IFB Module Testing

    Okay; its summertime and at least 50% of MSX owners must have broken IFB modules. I think a replacement item will be available soon but I need some assistance. Can a few of you perform the following test and see if this procedure really works? AND has anybody found where a defective PPU limited rpm, because I don't think its possible.. If you think you have a defective IFB SIFB, please do this test and let me know.
    To disable the IFB timeout for testing purposes.
    You must either start the PWC and then remove the lanyard to shut it down, OR just press the start button momentarily and then remove the lanyard.
    1. Wait 15 seconds
    2. Insert the lanyard and press the STOP button three (3) times within three seconds.
    3. Press the start button momentarily to enable the ECU without starting the engine OR start the engine normally.
    IF you enable the ECU with the System IFB in Diag Mode, the ECU will stay enabled until you press the stop button or remove the lanyard.



    To get the System IFB out of diagnostic mode:
    1. Either start the PWC OR press the start button momentarily to enable the ECU.
    2. Remove the Lanyard from the left hand control.
    3. Wait 10 15 seconds.




  2. #2
    ripcuda's Avatar
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    All this talk of PPUs and IFBs can be confusing. Just to help clarify...

    The Pedal Position Unit (PPU) and Pedal Position Unit Interface Box (PPU IFB)

    This is the PPU. It connects to the throttle on the handle bar via cable... then interprets this throttle input into an electrical signal. It is located behind the front storage bin next to the underside of the handlebar steering linkage.
    Click image for larger version. 

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    This is the PPU IFB. It takes the electric voltages (signals) from the PPU and interprets them for the ECU. It is located attached to the forward wiring harness on the right side of the ski... remove front storage bin to see it.
    Click image for larger version. 

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    Quote Originally Posted by Polaris Service Manual
    A unique function of the Bosch ME-- Motronic 7.4.4 Engine Management System is its use of a “Fly--By--Wire” or Electronic Throttle Control (ETC) system. In this system, the throttle flipper is not directly connected to the the throttle plate, but rather a pedal position unit or PPU.

    Four components make up the ETC system:
    - Pedal Position Unit (PPU)
    - Engine Control Unit (ECU)
    - Electronic Throttle Body (ETB)
    - PPU Interface Box (IFB)

    The PPU and ETB use two position sensors each to relay and verify the exact position of each component to the ECU. The ECU continuously monitors all four position sensors. In the event that any one sensor fails, the ECU will go into the LIMP--HOME mode, illuminate the CHECK ENGINE MIL light, and store the applicable trouble code


    The System Interface Box (SIFB... or System IFB)

    This is the SIFB. It takes the voltage inputs from the start/stop buttons, lanyard kill switch, and reverse switch and does stuff. It is located attached to the wiring harness on the right side, rear of the ski. Above the battery, below the ECU and main relay (brown box).
    Click image for larger version. 

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    Quote Originally Posted by Polaris Service Manual
    System Interface Box (SIFB)
    The primary function of the SIFB is to power--down the ignition system in the event that the lanyard is left inserted in the stop switch for more than two minutes. Without the SIFB, the ignition system would remain powered--up by the battery, and the battery would completely discharge. A secondary function of the SIFB is to convert the reverse switch signal so the ECU can interpret the signal when the reverse switch is closed, thereby limiting engine RPM.

    How It works
    The SIFB will disconnect the ECU ignition circuit and go into the “sleep” mode in the event that the lanyard is left installed in the stop switch for more than two minutes. This also holds true whenever the operator pushes the stop button momentarily while the engine is running. In the event that the operator removes the lanyard from the stop switch while the engine is running, the SIFB does nothing.

    To power--up the ECU after the SIFB has entered the “sleep” mode, the operator must re--insert (if removed) the lanyard into the stop switch, and press the start button.

    NOTE: The SIFB remains in the mode in which it was put into by the operator’s last action. For example, the SIFB will allow the ECU to power--up immediately when the lanyard is installed if the operator’s last action was removing the lanyard to kill the engine.

    Conversely, if the operator’s last action was leaving the lanyard in the stop switch for more than two minutes or stopping the engine by pushing the stop button, the ECU will not power--up until the SIFB “sees” a start signal gene

    Hope this helps. The SIFB is one of the leading electrical failures for the Weber engined, MSX 110 and 150 skis.

    Cheers!

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  4. #3

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    Quote Originally Posted by Weber Guy View Post
    Okay; its summertime and at least 50% of MSX owners must have broken IFB modules. I think a replacement item will be available soon but I need some assistance. Can a few of you perform the following test and see if this procedure really works? AND has anybody found where a defective PPU limited rpm, because I don't think its possible.. If you think you have a defective IFB SIFB, please do this test and let me know.
    To disable the IFB timeout for testing purposes.
    You must either start the PWC and then remove the lanyard to shut it down, OR just press the start button momentarily and then remove the lanyard.
    1. Wait 15 seconds
    2. Insert the lanyard and press the STOP button three (3) times within three seconds.
    3. Press the start button momentarily to enable the ECU without starting the engine OR start the engine normally.
    IF you enable the ECU with the System IFB in Diag Mode, the ECU will stay enabled until you press the stop button or remove the lanyard.



    To get the System IFB out of diagnostic mode:
    1. Either start the PWC OR press the start button momentarily to enable the ECU.
    2. Remove the Lanyard from the left hand control.
    3. Wait 10 15 seconds.
    I did this last year and it did indeed work on my ski. The ECU stayed powered up until I started my ski.

  5. #4

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    So this didn't allow you to ride the ski with a defective IFB, it just disables the "timeout" function?
    I don't see how this test would be useful to test for a defective IFB, am I missing something here? I'm attempting to find some simple tests for defective IFB & PPU modules, as the phone is ringing off the hook with questions.

    Thanks,
    Randy

  6. #5

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    I believe the main purpose of this diagnostic mode described is to power up the ECU for Digital Wrench and nothing more.

  7. #6
    jbo_92's Avatar
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    I had a bad IFB and the only way I could establish that it was bad was that the ski would crank only. No fuel pump, no gauge display, no throttle body, nothing electrical besides the starter.

  8. #7
    I'm addicted to Polaris PWC ghostinstallations's Avatar
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    What do people do when these fail other than look for a new one? Anyone just bypass the SIFB and / or add a relay for the reverse limiting? Sounds like a bypass would be a simple test for a faild SIFB if the failure resulted in a no start condition.

  9. #8
    ripcuda's Avatar
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    The reverse RPM limiting is a nice "feature" but not really critical. Most can go easy on the throttle when in reverse to not need it.

    However, these modules main duty is to power-up and power-down the system electronics. You might be able to bypass this sending direct voltage to the ECU which would power-up... but you'd also have to undo that to power-down or you'll drain your battery. Plus... not sure if this bypasses the stop/lanyard safety/kill switch... which would be undesirable, of course.

    Most folks just look for new ones... they want it to work like it used to.

    Cheers!

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