Hi,  First time user.  I have a 912 uls, year 2006, 100 HP, serial number 5460xx.  Engine ran good for a few flights this summer then suddenly no start.  Narrowed problem down to no spark from either module high voltage side of firing coils to the spark plugs.  I did the common high voltage side ohmmeter tests of the resister plugs, rubber plug caps, wires, and firing trigger coils by doing the across the engine plug boots from the cylinder pairs described in maintenance manual, with reliable ohm test results. 

New plugs set at .024 gap, as advised setting from readings about better starting.  Shortened spark plug wires at plug boots 1/4 inch before tests and re-connected firmly.  I have measured the ohms tests from both sides of the plug connectors to the modules and to the pulse generator and firing coils.  The tests are within the listed test diagrams in heavy maintenance manual.  There are two other six-pin connectors on the heavy maintenance manual diagram next to the six-pin modules diagram.  Where are those plug connectors?  I used two heavy duty industrial double pole 250 volt/20-amp switches for each module P lead grounding wires to stop each module's ignition.  I paralleled the wires on each switch for double ampacity and redundancy.  The ohmmeter testing of those switches tested as I would have expected.  Infinity for open and same ohms back to both modules from the switches.  I did see an entry someplace from 912 uls owners having manufactured years 2006, 2007, and 2008 engines and experienced module failures after only short hours of engine time.  My pictures show my modules are the green labeled types.  Some fellow airport members also said the yellow labeled modules are the more robust type. 

I have less than 500 hours on my engine since 2006.  Well maintained engine and proper storage procedures in always kept un-heated hanger.  Lots of medical issues preventing opportunities for me to fly.  Are the modules energized all the time?  Those second set of plugs in the diagram show a disconnect switch.  I read about incidents from others who had destruction of modules from connecting even for a few seconds a battery charger in reverse polarity.  I have one fuse to the ignition system at instrument panel and that is separated from power with a toggle switch at the instrument panel.  I don't see how reverse polarity charge would be a problem for the modules if they are separated from power when a battery would be charged.  I didn’t reverse polarity charge at any time, nor did I put any charger on the battery between my good flights and the no start day.  Just another curiosity about something I don't understand.  Are there any other fuses for the modules that I don’t know about?  In addition, any suggestions about alternative ignition modules to the Rotax parts providers for after-market modules in the US that would be more economical than Rotax and any information about their reliability?  When I did a search on the Internet for 912 uls 100 HP electronic ignition modules or capacitive discharge ignition modules, I couldn't even locate a source to find a price.  I read they are expensive, but why aren't they listed anywhere? 

I am from Wisconsin, near Green Bay.  Anyone have information about any companies that test and sell these modules?  Better yet would be technical reps that work for companies doing service for testing and selling the modules that I could contact for information first about steps for troubleshooting that I missed.  I am assuming other tests will show problems with my modules that will be a costly fix.  Any suggestions from guys who had similar experiences as mine, or anyone more experienced than me will be much appreciated.


Thanks for any advice in advance,       Jim  

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  • Re: Ignition Modules

    by » 2 years ago

    Hi Jim, Unfortunately this problem with the ignition modules is not uncommon :-(

    There are a range of faults with them including no spark on start-up. Assuming that this is the case with yours,
    then one of them probably failed some time ago but you didn't notice because they work OK when the engine is running
    and you can successfully start with a single module.

    There is no connection between the battery and the ignition modules, they are powered from 2 independent sets of
    charging coils on the back of the engine. There is no fusing in the ignition circuitry so if you have good ground connections,
    the charging coils are connected and the engine is turning fast enough then you will get a spark. Your options for replacing the modules are:

    1. Buy new Rotax ones (quite expensive).

    2. Buy some second-hand ones (if you can find any).

    3. Send them to Carmo Electronics in the Netherlands for repair (I have done this but sometimes it takes them a couple of
    goes to get it right).

    4. Mark Kyle in Australia is manufacturing uprated replacement modules.

    5. Many owners in the UK are fitting Ignitech replacement modules. https://www.ignitech.cz/en/vyrobky/bikes/rotax/rotax%20912%20and%20914/rotax%20912%20and%20914.htm

    You can diagnose the ignition starting issue by either heating or cooling the modules on the engine using a hair drier or
    an ice bag. Bear in mind that the modules are fully potted so it will take a while for the heat to penetrate.

    There are multiple other threads on the Rotax SMD ignition modules on this forum.
    A search should reveal some useful posts. Good luck!

  • Re: Ignition Modules

    by » 2 years ago

    Thank you, Kevin         

    You have given me much to work with.  I appreciate that.


  • Re: Ignition Modules

    by » 2 years ago

    I just realized now that the two other six-pin drawings on the heavy maintenance manual next to the diagram are views of the six-pin connectors looking at the pins.  Anxiety makes me miss simple things.  No fun here being grounded.

  • Re: Ignition Modules

    by » 2 years ago

    https://lockwood.aero/965-444-6-6-pin-soft-start-module.html          These are the modules installed in my 2005 ULS April this year.

  • Re: Ignition Modules

    by » 2 years ago

    Recently I installed two Igni-Tech DCCDIP2 modules from the Czech Republic on my 1991 model 912UL (suggestion #5). Over the past 7 days I have about 10 hours logged of perfect performance. Five of those hours were on last Saturday. After installation the engine roared to life the moment I first hit the starter. I was told these CDIs are certified in Europe. They have the “soft start” and can also be rigged for instant spark.

    They are well manufactured and I like ‘em.

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