SFI SYSTEM, Diagnostic DTC:U0101

DTC Code DTC Name
U0101 Lost Communication with TCM

DESCRIPTION

The Transmission Control Module (TCM) and ECM perform 2-way communication with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine speed, required engine torque, warning indicators in the combination meter assembly, DTCs and other data. The ECM sends signals to the TCM concerning engine speed, opening angle of the throttle valve, temperature of intake air, temperature of engine coolant, engine torque 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. Ignition switch ON

    2. Battery voltage 10.5 V or more

    3. No intercommunication between ECM and TCM

  • ECM to TCM circuit

  • TCM

  • ECM

CONFIRMATION DRIVING PATTERN


  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON and turn the GTS on.

  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.

  4. Turn the ignition switch off and wait for at least 30 seconds.

  5. Turn the ignition switch to ON and turn the GTS on.

  6. Wait 5 seconds or more.

  7. Enter the following menus: Powertrain / Engine / Trouble Codes.

  8. Read the pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  9. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  10. Input the DTC: U0101.

  11. Check the DTC judgment result.

    GTS Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions
    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result shows INCOMPLETE or N/A, perform the Confirmation Driving Pattern and check the DTC judgment result again.

WIRING DIAGRAM

A01EKD3E18

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips

Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC U0101)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine / Trouble Codes.

    5. Read the DTCs.

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

      Tech Tips

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


    B

    GO TO DTC CHART Click here

    A

  2. INSPECT ECU POWER SOURCE CIRCUIT (TCM POWER SOURCE)


    1. A01EIZPE10
      Text in Illustration
      *a

      Front view of wire harness connector

      (to TCM)

      Disconnect the TCM connector.

    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
      B40-1 (BATT) - B40-8 (E1) Always 11 to 14 V
      B40-18 (+B) - B40-8 (E1) Ignition switch ON 11 to 14 V
      Result
      Result Proceed to
      OK A
      NG (for U760E) B
      NG (for U760F) C

    B

    GO TO TCM POWER SOURCE CIRCUIT Click here

    C

    GO TO TCM POWER SOURCE CIRCUIT Click here

    A

  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
      Tester Connection Condition Specified Condition
      B40-6 (CAN+) - B58-24 (CAN+) Always Below 1 Ω
      B40-7 (CAN-) - B58-1 (CAN-) Always Below 1 Ω
      B40-6 (CAN+) or B58-24 (CAN+) - Body ground Always 10 kΩ or higher
      B40-7 (CAN-) or B58-1 (CAN-) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (for U760E) A
      OK (for U760F) B
      NG C

    B

    REPLACE TCM Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - TCM)

    A

  4. REPLACE TCM


    1. Replace the TCM (for U760E) Click here.


    NEXT

    CHECK WHETHER DTC OUTPUT RECURS (DTC U0101) Click here

  5. REPLACE TCM


    1. Replace the TCM (for U760F) Click here.


    NEXT

  6. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine / Trouble Codes.

    5. Read the DTCs.

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

    B

    REPLACE ECM Click here

    A

    END