ECD 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 stores a DTC.

DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Ignition switch ON for 3 seconds

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


  • The battery voltage is 10.5 V or higher.

  • No intercommunication between the ECM and TCM.

  • ECM

  • TCM

  • ECM to TCM circuit

WIRING DIAGRAM

A004RQXE08
*1 from EFI MAIN Relay

PROCEDURE


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


    1. Connect the intelligent tester to the DLC3.

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

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

    4. 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 (POWER SOURCE, BODY GROUND)


    1. A004NFTE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to TCM)

      Disconnect the TCM connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      B77-18 (+B) - B77-8 (E1) Ignition switch ON 11 to 14 V

    3. Turn the ignition switch off.

    4. Reconnect the TCM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM)


    1. Disconnect the TCM connector.

    2. Disconnect the ECM connector.

    3. A004MOTE02
      *a

      Front view of wire harness connector

      (to ECM)
      *b

      Front view of wire harness connector

      (to TCM)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B39-40 (CAN+) - B77-6 (CAN+) Always Below 1 Ω
      B39-63 (CAN-) - B77-7 (CAN-) Always Below 1 Ω
      B39-40 (CAN+) or B77-6 (CAN+) - Body ground or other terminals Always 1 MΩ or higher
      B39-63 (CAN-) or B77-7 (CAN-) - Body ground or other terminals Always 1 MΩ or higher

    4. Reconnect the TCM connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE ECM


    1. Replace the ECM Click here.


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)


    1. Connect the intelligent tester to the DLC3.

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

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

    4. Read the DTCs.

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

    A

    END

    B

    REPLACE TCM Click here