AUTOMATIC TRANSMISSION SYSTEM, Diagnostic DTC:U0100

DTC Code DTC Name
U0100 Lost Communication with ECM / PCM "A"

DESCRIPTION

The ECM communicates with the TCM using the Controller Area Network (CAN).

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

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
U0100 Lost Communication with ECM / PCM "A"

All conditions are met for 1.25 seconds (1-trip detection logic):


  • Ignition switch is ON.

  • Battery voltage is 10.5 V or higher.

  • There is no communication between the ECM and TCM.

  • Harness or connector

  • ECM

  • TCM

 Comes on DTC stored

WIRING DIAGRAM

A01WARZE03
*a from EFI-MAIN NO. 1 Relay
*b CAN Communication Line

CAUTION / NOTICE / HINT

Tech Tips


  • Refer to the inspection procedure for the CAN communication system.

  • If the CAN communication malfunctions, the TCM cannot receive current data from the ECM. In this case, the freeze frame data output from the TCM has not been updated so the data will not be useful for the inspection. However, reading the Data List as the first step in troubleshooting is an effective way to find malfunctions.

  • The malfunctioning area can be confirmed using the Bus Check function of the GTS.

    for LHD:

    Click here

    for RHD:

    Click here

  • After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.


    1. Check that the battery voltage is 10.5 V or higher.

    2. Turn the ignition switch to ON.

    3. Check for DTCs again.

      Click here

PROCEDURE


  1. CHECK TERMINAL VOLTAGE (POWER SOURCE OF ECM)


    1. A01WBOVC01
      *a

      Rear view of wire harness connector

      (to ECM)

      Disconnect the ECM 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
      G84-1 (+B) - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ECM POWER SOURCE CIRCUIT Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)


    1. A01W9PQC01
      *a

      Rear view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C56-7 (E1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM)


    1. Disconnect the G83 ECM connector.

    2. Disconnect the G90 TCM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G83-22 (CAN+) - G90-21 (CAN+) Always Below 1 Ω
      G83-21 (CAN-) - G90-20 (CAN-) Always Below 1 Ω
      G83-22 (CAN+) or G90-21 (CAN+) - Body ground or other terminals Always 10 kΩ or higher
      G83-21 (CAN-) or G90-20 (CAN-) - Body ground or other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE TCM


    1. Replace the TCM.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  5. CHECK DTC OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Click here


      Powertrain > ECT > Clear DTCs

    5. Start the engine.

    6. Enter the following menus: Powertrain / ECT / Trouble Codes.


      Powertrain > ECT > Trouble Codes

    7. Read the DTCs using the GTS.

      Result
      Result Proceed to
      DTCs are not output A
      U0100 is output B

    A

    END

    B

    REPLACE ECM Click here