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Thread: "wakeup serial data" LMM stand alone harness

  1. #1
    Junior Member
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    Apr 2021
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    Default "wakeup serial data" LMM stand alone harness

    I am getting P2536, U0140 and U0121 codes, I have found some reference to P2536 being the absence of 5V or greater on pin 43 of the TCM in the accessory position (signal comes from the BCM which of course is no longer there), there is no connection from the accessory terminal of the ignition switch and the stand alone harness, there is zero volts on pin 43 in any ignition position, is this correct?
    I have U0140 deleted from the ECM DTCs but cannot find U0121 or P2536 in the tune and in any case I am still getting the U0140 code.
    THANKS!!
    Last edited by Papalote; May 13th, 2021 at 01:25 PM.

  2. #2
    Junior Member
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    Apr 2021
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    17

    Default

    Thanks to some PM help I have connected the "wakeup" pins on both the TCM and ECM to ignition and the P2536 code has gone away, I am still getting the U0140 and U0121 any suggestions would be appreciated

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