ECD SYSTEM, 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 Detection Drive Pattern DTC Detection Condition Trouble Area
Ignition switch to ON for 3 seconds

Both 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

WIRING DIAGRAM

A003F9OE01

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 running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

PROCEDURE


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


    1. Connect the GTS to the DLC3.

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

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

    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 TCM POWER SOURCE CIRCUIT (POWER SOURCE AND BODY GROUND)


    1. A003C8EE29
      Text in Illustration
      *a

      Rear 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
      O3-5 (BATT) - O1-1 (E1) Ignition switch ON 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B88-4 (CAN+) - O3-21 (CAN+) Always Below 1 Ω
      B88-5 (CAN-) - O3-20 (CAN-) Always Below 1 Ω
      B88-4 (CAN+) or O3-21 (CAN+) - Body ground or other terminals Always 1 MΩ or higher
      B88-5 (CAN-) or O3-20 (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 GTS to the DLC3.

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

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

    4. Read the DTCs.

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

    B

    REPLACE TCM

    A

    END