ECD SYSTEM(for CCo), Diagnostic DTC:U0101

DTC Code DTC Name
U0101 Lost Communication with TCM

DESCRIPTION

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

If there is a problem with this communication, the ECM stores a DTC.

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

The following conditions are met for 1.25 seconds (1 trip detection logic):


  • The battery voltage is 10.5 V or higher.

  • No communication between the ECM and TCM.

  • ECM

  • TCM

  • ECM to TCM circuit

 Comes on DTC stored

CONFIRMATION DRIVING PATTERN

DTC No. DTC Detection Drive Pattern
U0101 Ignition switch ON for 3 seconds

WIRING DIAGRAM

A01QRSJE07
*1 from EFI MAIN NO. 1 Relay

CAUTION / NOTICE / HINT

Note

After replacing the ECM, the new ECM needs registration (Click here ) and initialization Click here.

PROCEDURE


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


    1. Connect the GTS to the DLC3.

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

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


      Powertrain > Engine > Trouble Codes

    4. Read the DTCs.

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

      Tech Tips

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


    DTC U0101 and other DTCs are output

    GO TO DTC CHART Click here

    DTC U0101 is output

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF TCM)


    1. A01QRMUC07
      *1

      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
      B79-18 (+B) - B79-8 (E1) Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM)


    1. A01QRHHC01
      *1

      Front view of wire harness connector

      (to ECM)
      *2

      Front view of wire harness connector

      (to TCM)

      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
      B76-40 (CAN+) - B79-6 (CAN+) Always Below 1 Ω
      B76-63 (CAN-) - B79-7 (CAN-) Always Below 1 Ω
      B76-40 (CAN+) or B79-6 (CAN+) - Body ground Always 10 kΩ or higher
      B76-63 (CAN-) or B79-7 (CAN-) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    GO TO STEP 7 Click here

    OK

  4. REPLACE ECM


    1. Replace the ECM.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (IN ADDITION TO DTC U0101)


    1. Connect the GTS to the DLC3.

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

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


      Powertrain > Engine > Trouble Codes

    4. Read the DTCs.

      Result
      Proceed to
      DTC is not output
      DTC U0101 is output

    DTC is not output

    END

    DTC U0101 is output

  6. REPLACE TCM


    1. Replace the TCM.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 8 Click here

  7. REPAIR OR REPLACE HARNESS OR CONNECTOR


    1. Repair or replace the harness or connector.

      Result
      Proceed to
      NEXT

    NEXT

  8. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the GTS to the DLC3.

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

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


      Powertrain > Engine > Trouble Codes

    4. Confirm that the DTC is not output again.

      Result
      Proceed to
      NEXT

    NEXT

    END