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Thread: U0101 - TCM not communicating - 2010 CTS-V

  1. #1
    Potential Tuner
    Join Date
    Sep 2017
    Posts
    5

    U0101 - TCM not communicating - 2010 CTS-V

    Code U0101 came up today while I was working on buttoning up a twin turbo build. I poked around with HPTuners to see if I could read the TCM but it says "Requesting access.....Connection Timed Out..........FAILED" and I can't get it to connect. Communication with the ECM works fine (Read and write).

    I unplugged everything from the ODBII port, disconnected the battery for 1/2 hour hoping to reset the CAN, checked the plug / wires / pins / connector in the trans and blew some air in them to remove any possible debris, cleaned the battery posts and all the grounds, cleared the codes and it comes back immediately when I turn the key on.

    "Stabilitrac Off"
    "Parking assist Off"
    "Service Stabilitrac"
    "Service Tire Monitor System"
    "Service Traction Control"

    The car is stuck in some type of "limp" mode and seems like it is stuck in 3rd gear (Reverse works too). No gear indicator on the dash either.

    I drove it two days ago while logging some around town driving and zero transmission related problems.

    Not sure what else I could try to get this bitch to recognize the TCM at all.

    Any suggestions or recommendations are welcome!

  2. #2
    Tuner
    Join Date
    Jul 2018
    Location
    Texas
    Posts
    53
    #PIC5630: Intermittent No Crank U0100 U0101 U0121 - (Apr 17, 2013)
    Subject:
    Intermittent No Crank U0100 U0101 U0121


    Models:
    2008 - 2012 Cadillac CTS
    With 6-Speed Automatic Transmission

    The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
    Condition/Concern:
    A customer may comment about an intermittent no crank / no start and/or an intermittent SES lamp illuminated. Diagnostics may reveal a U0100, U0121 and/or a U0101 with a possible no communication with the TCM, EBCM, and/or ECM.
    Recommendation/Instructions:
    Please check the round connector at the transmission control module (Control Solenoid Valve Assembly) for possible High Speed LAN wire/wires that may be pushed out of the back of the connector.
    After locating the high speed LAN wires gently pull out on the wires to make sure they are seated correctly. It has been noted that the terminals are pushed back out of the connector body with damaged lock tabs on the terminal. If this issue is confirmed, please replace the suspect terminal(s) and re-test.
    Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
    Attached Images Attached Images
    Last edited by DGS; 1 Week Ago at 07:51 PM.