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Fuse Box Circuitry

in 912iS Technical Questions 8 years ago
Does anyone have a circuit diagram of the 912iS Fuse box?

In particular, the X3 connector, the Rectifiers, Relays, and Capacitors.
How are these all connected?

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

  • Re: Fuse Box Circuitry

    by » 8 years ago

    I need the same. I have problem with X1 connector.
      
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  • Re: Fuse Box Circuitry

    by » 8 years ago

    I hope the Inside People at Rotax can help here. Hint! Hint! :whistle:

    I can not find any published documentation on this subject.
    The wiring harness, fuse box, and ECU are all treated as SECRET.
    I can understand the ECU being proprietary.
    But the Wiring Harness and Fuse Box Info would sure help in troubleshooting Problems.

    There is enough info available on the X1 and X2 connectors that Pulling all the fuses and tracing the pins with an Ohm-Meter should not be overly difficult to reverse engineer.
    They are mostly just the fused +12v supplies for all the sensors.

    I have started Reverse Engineering the X3 connector.
    It goes to the relays and then on to the outputs of the two alternators.
    What gets connected when is a little more complicated.

    Pin #1 (Backup Power) Appears to be a direct connection to the ECU +12v Master Buss.
    Pin #2 (Start Power) This is still a Grey Area. ???
    Pin #3 (+12v Power Out) Connects through a Relay to the 35A Fuse of the +12v Gen-B output.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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  • Re: Fuse Box Circuitry

    by » 8 years ago

    Hi Bill, There are no direct factory participants on this forum, it is for owners only.
      
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  • Re: Fuse Box Circuitry

    by » 8 years ago

    I agree with you Bill, while I am sure that Rotax have done and excellent job in designing and making this engine, it would be good if Rotax could explain a little more of their thinking. I am building an aircraft, I have the engine. I will be flying far from any engineering assistance so I would appreciate knowing more about what Rotax ideally wants in an installation.

    If you look at the first editions of the wiring diagram compared to the current one, you will notice that the power wiring has been upgraded from 14 AWG to 12 AWG. When you also consider that Rotax has upgraded the B Generator stator wiring as well, it is starting to sound like Rotax might not have completely anticipated the electrical load that all our fancy modern electronics apply.

    When you tell me that the Rotax "B" alternator is fused to 35 amps, then it suggests to me that best aircraft electrical practice would be to make the wire from Pin 3 of the X connector to the battery of 10 AWG not 12 AWG. I have tracked down and bought the special pin to do this.

    I will also try and track down on the internet the instructions for fitting the (Molex) HIC connector pins because I have lost the reference. I did buy some extra pins for that as well. Without Robs helpful diagram I would never have noticed that there are Two different wire sizes and associated pins on the HIC.

    If I can find the reference for the installation of Molex pins I will post the link.
      
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  • Re: Fuse Box Circuitry

    by » 8 years ago

    Found the link. I think the HIC is a Molex 150 series connector

    Product brochure and instructions.

    http://www.mouser.com/pdfdocs/MolexMX150SealedConnectorSystem.pdf



    http://datasheet.octopart.com/0194200009-Molex-datasheet-510632.pdf

    The Molex brochure says that the contacts are rated to 18 Amps (or is it 22 amps?). The contacts are also limited to 25 cycles (insert/remove) unless they are the gold plated ones which are good for 100 cycles.
      
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