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 the Controller Area Network (CAN).

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"

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


  • Ignition switch ON

  • Battery voltage is 10.5 V or more

  • No communication between the engine control ECU (ECM) and TCM

  • Harness and connector

  • ECM

  • TCM

 Comes on DTC stored

WIRING DIAGRAM

A018LJWE01

CAUTION / NOTICE / HINT

Tech Tips


  • Refer to inspection procedure for CAN communication system.

  • If the CAN communication malfunctions, the TCM cannot receive the 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 effective to find malfunctions.

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

    Click here

PROCEDURE


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


    1. A018ITDC16
      *a

      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
      C3-18 (+B) - C3-8 (E1) Ignition switch ON 9 to 14 V

    4. Turn the ignition switch off.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C3-8 (E1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (TCM - ECM)


    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
      C3-6 (CAN+) - C1-31 (CAN+) Always Below 1 Ω
      C3-7 (CAN-) - C1-1 (CAN-) Always Below 1 Ω
      C3-6 (CAN+) or C1-31 (CAN+) - Body ground and other terminals Always 10 kΩ or higher
      C3-7 (CAN-) or C1-1 (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 a 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