AUTOMATIC TRANSAXLE SYSTEM, Diagnostic DTC:U0100

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

DESCRIPTION

The engine control unit communicates with the TCM using CAN communication.

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

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

1. Diagnosis Condition 2. Malfunction Status 3. Malfunction Time 4. Other


  1. The engine switch is on (IG) and battery voltage is 10.5 V or more.

  2. No communication between engine control ECU (ECM) and TCM

  3. 1.25 seconds or more

  4. 1-trip detection logic

  • Harness and connector

  • ECM

  • TCM

 Comes on DTC stored

WIRING DIAGRAM

A01UFJHE01
*a from EFI NO. 4 Fuse
*b CAN Communication Line

CAUTION / NOTICE / HINT

Note


  • Perform registration and/or initialization when parts related to the automatic transaxle are replaced.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips


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

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

  • The malfunction area can be checked by using the Bus Check function of the GTS.

    for LHD: Click here

    for RHD: Click here

  • After performing 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 more.

    2. Turn the engine switch on (IG).

    3. Check for DTCs again.

      Click here

PROCEDURE


  1. CHECK ECU TERMINAL VOLTAGE (+B AND E1 TERMINALS)


    1. Disconnect the D39 TCM connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      D39-18 (+B) - D39-8 (E1) Engine switch on (IG) 11 to 14 V

    4. Turn the engine switch off.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D39-8 (E1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    GO TO ECU POWER SOURCE CIRCUIT Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (TCM - ECM)


    1. Disconnect the D39 TCM connector.

    2. Disconnect the D73 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D39-6 (CAN+) - D73-31 (CAN+) Always Below 1 Ω
      D39-7 (CAN-) - D73-1 (CAN-) Always Below 1 Ω
      D39-6 (CAN+) or D73-31 (CAN+) - Body ground and other terminals Always 10 kΩ or higher
      D39-7 (CAN-) or D73-1 (CAN-) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK IF DTC OUTPUT RECURS


    1. Connect the GTS to the DLC3.

    2. Clear the DTCs.


      Powertrain > ECT > Clear DTCs

    3. Replace the TCM.

      Tech Tips

      Replace the TCM with the TCM from a normally functioning vehicle of the same model.

    4. Start the engine.

    5. Read the DTCs.


      Powertrain > ECT > Trouble Codes
      Result
      Result Proceed to
      DTC U0100 is output A
      DTCs are not output B

    A

    REPLACE ECM Click here

    B

    REPLACE TCM Click here