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About what the title says. Servo cycles, but no flashes from the TCU lights. Checked the continuity of the wires (they go to a terminal strip on the firewall) and they're fine, as are the bulbs. 

 

Thoughts?

 

TIA

  • Re: 914 first powerup- no TCU caution or warning lights

    by » 3 weeks ago


    If the servo cycles at power-up, the TCU is powered and functioning, that’s the “built-in self-check”

    The TCU does not power the caution or warning lights; it only switches them to ground. The lamps must have aircraft +12 V on one side. If neither light comes on (even briefly), it’s almost always a lamp power, ground reference, or pinning issue, not a bad TCU.

    Common on first installs:

    • No +12 V to the lamps
    • Lamps wired expecting the TCU to supply power
    • Incorrect ground reference
    • Mis-pinned wires at the firewall terminal strip

    Quick test: With the master on, momentarily ground the lamp wire; if it lights, the issue is with the wiring to the TCU.

    Servo cycles = TCU is alive.

    I have attached a document titled "Understanding the Rotax 914," and here is the link for you to download the 914 installation manual.

     https://www.rotax-owner.com/en/support-topmenu/engine-manuals#current-engines

    44129_2_understanding-the-rotax-914.pdf (You do not have access to download this file.)

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