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SFI SYSTEM, Diagnostic DTC:U0101

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DTC Code DTC Name
U0101 Lost Communication with TCM
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DESCRIPTION

The Transmission Control Module (TCM) and ECM perform 2-way communications with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine rpm, required engine torque, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine rpm, opening angles of the throttle valve, temperature of intake air, temperature of engine coolant, engine torques and other data. If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.

DTC No. DTC Detection Condition Trouble Area
U0101

  • Following conditions are met for 1.25 seconds (1 trip detection logic):


    1. Engine switch on (IG)

    2. Battery voltage 10.5 V or more

    3. No intercommunication between ECM and TCM

  • ECM to TCM circuit

  • TCM

  • ECM
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WIRING DIAGRAM

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INSPECTION PROCEDURE

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PROCEDURE


  1. Click here

    CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC U0101)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine / DTC.

    5. Read the DTCs.

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

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


  2. Click here

    INSPECT ECU POWER SOURCE CIRCUIT (TCM POWER SOURCE)


    1. A01CCLHE01

      Disconnect the TCM connector.

    2. Turn the engine switch on (IG).

    3. Measure the resistance according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D4-1 (BATT) - Body ground Always 11 to 14 V
      D4-18 (+B) - Body ground Engine switch on (IG) 11 to 14 V

    4. Reconnect the TCM connector.


  3. Click here

    CHECK HARNESS AND CONNECTOR (ECM - TCM)


    1. A01CFOHE01

      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
      D4-6 (CAN+) - D1-2 (CAN+) Always Below 1 Ω
      D4-7 (CAN-) - D1-1 (CAN-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D4-6 (CAN+) or D1-2 (CAN+) - Body ground Always 10 kΩ or higher
      D4-7 (CAN-) or D1-1 (CAN-) - Body ground Always 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reconnect the TCM connector.


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    REPLACE ECM


    1. Replace the ECM (Click here).


  5. Click here

    CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the tester on.

    3. Enter the following menus: Powertrain / Engine / DTC.

    4. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC U0101 is output B

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    GO TO DTC CHARTClick here

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    GO TO TCM POWER SOURCE CIRCUITClick here

  8. Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)

  9. Click here

    END

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    REPLACE TCMClick here