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SFI SYSTEM(w/o Canister Pump Module), 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 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 communication system, illuminate the MIL and store this DTC.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
U0101 Lost Communication with TCM

All of the following conditions are met for 1.25 seconds (1 trip detection logic):


  1. Engine switch on (IG)

  2. Battery voltage 10.5 V or higher

  3. No communication between ECM and TCM

  • ECM to TCM circuit

  • TCM

  • ECM

 Comes on DTC stored
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MONITOR STRATEGY

Required Sensors/Components ECM
Frequency of Operation Continuous
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CONFIRMATION DRIVING PATTERN


  1. Connect the GTS to the DLC3.

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

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

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

  5. Turn the engine switch on (IG) 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.

    Tip:

    • 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's memory limit
    Tip:

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

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

Table 1. *a from EFI-MAIN Relay *b from P/I-B Fuse *c EFI-MAIN *d CAN Communication Line
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WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Note:

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

Tip:

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.

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PROCEDURE


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


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: System Select / Health Check.

    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. *a Front view of wire harness connector (to TCM)
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    CHECK TERMINAL VOLTAGE (POWER SOURCE OF TCM)


    1. Disconnect the TCM connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A79-6 (BATT) - A79-2 (E1) Always 11 to 14 V

    3. Turn the engine switch on (IG).

    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A79-5 (+B) - A79-2 (E1) Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

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    CHECK HARNESS AND CONNECTOR (TCM - ECM)


    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
      A79-21 (CAN+) - A78-9 (CAN+) Always Below 1 Ω
      A79-13 (CAN-) - A78-10 (CAN-) Always Below 1 Ω
      A79-21 (CAN+) or A78-9 (CAN+) - Body ground Always 10 kΩ or higher
      A79-13 (CAN-) or A78-10 (CAN-) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    • OKClick here
    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR

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    REPLACE TCM


    1. Replace the TCM.

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      Result
      Proceed to
      NEXT

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    CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.

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      1. Powertrain > Engine > Clear DTCs


    5. Turn the engine switch off and wait for at least 30 seconds.

    6. Turn the engine switch on (IG) and turn the GTS on.

    7. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

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

    9. Read the DTCs.


      1. Powertrain > Engine > Trouble Codes


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