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Thread: trans code

  1. #1
    eldog90's Avatar
    eldog90 is offline Cadillac Owners Member
    Automobile(s): 1996 deville
    Join Date
    Jul 2003

    trans code

    can anyone shed some light on the code po56? what does it mean,how to correct it and does it affect thr driveabilty of the car?how major or minor is this code.the car is a 95 sls with 116,000 on the clock

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  3. #2
    Join Date
    Feb 2003

    Re: trans code

    Test conditions

    1. Codes p024, p075, and p091 NOT set
    2. Trans not in neutral or park
    3. engine running.
    4. vehicle speed greater than 10 MPH

    Failure condition

    1. Input shaft speed 50 RPM or less for 2 seconds.

    Action taken

    1. Turn on SES lamp
    2. PCM calculates input speed based on output speed and gear ratio.
    3. PCM calculates slip speed using calculated input speed.
    4. TCC engaged
    5. garage shift adapts frozen at current level
    6. shift adapts frozen at current level
    7. Torque management disabled.



  4. #3
    Join Date
    Feb 2003

    Re: trans code

    To diagnose

    WIth engine running and trans in park check PD72

    If greater than 100 rpm the fault is not present check for EMI sources near wiring and wait for fault to reappear

    If less than 100 RPM then turn engine off and disconnect trans connector. Measure frequency between a and b pins on trans with engine running and in park.

    0 hz then check wiring in trans. If no problems found then replace inupt sensor.

    Not 0 hz then turn engine of and reconnect connector. Back probe terminals 1b3 and 1b4 at PCM

    0 hz then repair wiring between trans and pcm.

    not 0 hz then inspect terminals 1b3 and 1b4. If ok then replace PCM.

    The sensor was a common failure point and a good bet if you can't perform the diagnosistic.




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