SFI SYSTEM, Diagnostic DTC:U0101

DTC Code DTC Name
U0101 Lost Communication with TCM

DESCRIPTION

The ECM (engine control unit) intercommunicates with the TCM (transmission control ECU) through the Controller Area Network (CAN).

If there is a problem in this intercommunication, the ECM sets 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 is 10.5 V or more

    3. No intercommunication between engine control ECM and TCM

  • ECM

  • TCM

  • ECM to TCM circuit

MONITOR STRATEGY

Required Sensors/Components (Main) ECM
Frequency of Operation Continuous

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) Click here.

  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 DTCs.

    Tech Tips


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

    • If a 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

    Tech Tips

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

WIRING DIAGRAM

A01FEENE01

INSPECTION PROCEDURE

PROCEDURE


  1. 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: Powertrain / Engine / Trouble Codes.

    5. Read DTCs.

      Result
      Display (DTC output) Proceed to
      U0101 A
      U0101 and other DTCs 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 TCM


    1. A01FEYOE09
      Text in Illustration
      *a

      Front view of wire harness connector

      (to TCM)

      Disconnect the A74 TCM connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A74-6 (BATT) - Body ground 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 Switch Condition Specified Condition
      A74-5 (+B) - Body ground Engine switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A74-2 (E1) - Body ground Always Below 1 Ω

    NG

    GO TO TCM POWER SOURCE CIRCUIT Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM)


    1. Disconnect the A21 ECM connector.

    2. Disconnect the A74 TCM connector.

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

      Standard Resistance (Check for open)
      Tester Connection Condition Specified Condition
      A21-9 (CAN-) - A74-13 (CAN-) Always Below 1 Ω
      A21-10 (CAN+) - A74-21 (CAN+) Always Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      A21-9 (CAN-) or A74-13 (CAN-) - Body ground Always 10 kΩ or higher
      A21-10 (CAN+) - A74-21 (CAN+) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE TCM


    1. Replace the TCM Click here.


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)


    1. Connect the GTS to the DLC3.

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

    3. Clear the DTCs Click here.

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

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

    8. Read DTCs.

      Result
      Display (DTC output) Proceed to
      No output A
      U0101 B

    B

    REPLACE ECM Click here

    A

    END

  6. REPLACE ECM


    1. Replace the ECM Click here.