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Thread: ECM 1227747 Wiring - Pin "C9"

  1. #1
    Carb and Points!
    Join Date
    Aug 2018
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    ECM 1227747 Wiring - Pin "C9"

    New member - assistance required with 1227747 which is installed in a 81 Jeep CJ5 with SBC350

    I've been tracking down a "no starter" condition that was occurring only after driving for a period. After many steps of problem determination, it was found that the problem is not the start/solenoid but the starter wire from the ignition switch. Tracing this wire back from the solenoid I've located a splice that branches off and connects to Pin "C9" of the ECM. The documentation available indicates this is the "crank signal"; however, I'm questioning the original work done during engine swap and perhaps a misinterpretation of the term "crank signal".

    Is connecting pin C9 to the starter/solenoid correct or is pin C9 for the crank position sensor as the information uncovered suggests? Or perhaps the connection is needed for some undetermined reason on this "Franken-Jeep".

    Appreciate any assistance/guidance.

  2. #2
    Carb and Points!
    Join Date
    Aug 2018
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    Not long after posting my question re: pin C9 the following was found in a larger wiring diagram.
    C9 Wiring Diagram.JPG
    From this diagram the wiring to C9 is correct. I suspect now the issue is the ECM failing.
    In light of this new information, does anyone have a pointer to what this "crank signal" does for the ECM

  3. #3
    Fuel Injected!
    Join Date
    Dec 2012
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    Naches, WA
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    You do not say if things to cool down the engine will re-start or not. If so, before declaring a failing ECM, I would look at the ignition control module. I have experienced a situation where the heat transfer compound under the ICM dried out and wasn't transferring heat. Cleaning things up and new compound fixed the issue.

  4. #4
    Super Moderator dave w's Avatar
    Join Date
    Feb 2011
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    6,268
    I suspect the function for the "Crank" signal is for the ECM to enter a different injector firing routine when the engine is cranking. Newer computers have several parameters for "Start" programming.

    dave w

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