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DTC U0101: Lost Communication with TCM [12/2015 - 08/2016]: Procedure

WARNING: This page is about a different car, the 2016 Toyota Sienna. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC U0101) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read DTCs.
      RESULT

      Result Proceed to
      DTC U0101 is output A
      DTC U0101 and other DTCs are output B

      HINT: 

      If any DTCs other than U0101 are output, troubleshoot those DTCs first.

    Result: 

    B 

    GO TO DTC CHART 

    (Refer to DIAGNOSTIC TROUBLE CODE CHART [12/2015 - 08/2016] )

    Result: 

    A 

    See step  2

  2. INSPECT ECU POWER SOURCE CIRCUIT (TCM POWER SOURCE) 
    1. Disconnect the TCM connector.
      GTY739476Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      B2-1 (BATT) - B2-8 (E1) Always 11 to 14 V
      B2-18 (+B) - B2-8 (E1) Ignition switch ON 11 to 14 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to TCM)

    Result: 

    NG 

    GO TO TCM POWER SOURCE CIRCUIT 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM) 
    1. Disconnect the TCM connector.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      B2-6 (CAN+) - B1-24 (CAN+) Always Below 1 Ω
      B2-7 (CAN-) - B1-1 (CAN-) Always Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      B2-6 (CAN+) or B1-24 (CAN+) - Body ground Always 10 kΩ or higher
      B2-7 (CAN-) or B1-1 (CAN-) - Body ground Always 10 kΩ or higher

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. REPLACE ECM 
    1. Replace the ECM (Refer to REMOVAL [12/2015 - 08/2016] ).

    Result: 

    NEXT 

    See step  5

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read DTCs.
      RESULT

      Result Proceed to
      DTC is not output A
      DTC U0101 is output
      (for 2WD)      		 B
      DTC U0101 is output
      (for AWD)      		 C

    Result: 

    A 

    END 

    Result: 

    B 

    REPLACE TCM (FOR 2WD) 

    (Refer to REMOVAL [12/2015 - 08/2016] )

    Result: 

    C 

    REPLACE TCM (FOR AWD) 

    (Refer to REMOVAL [12/2015 - 08/2016] )

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