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 sets a DTC.

DTC No. DTC Detection Condition Trouble Area
U0100

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 and TCM

  • Harness and connector

  • ECM

  • TCM

WIRING DIAGRAM

A01EKRXE06

INSPECTION PROCEDURE

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. A01ELIEE22
      Text in Illustration
      *1

      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 Switch Condition Specified Condition
      B40-18 (+B) - B40-8 (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
      B40-8 (E1) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (TCM - ECM)


    1. A01EIU6E22
      Text in Illustration
      *1

      Front view of wire harness connector

      (to ECM)
      *2

      Front view of wire harness connector

      (to TCM)

      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
      B40-6 (CAN+) - B58-24 (CAN+) Always Below 1 Ω
      B40-7 (CAN-) - B58-1 (CAN-) Always Below 1 Ω
      B40-6 (CAN+) or B58-24 (CAN+) - Body ground or other terminals Always 1 MΩ or higher
      B40-7 (CAN-) or B58-1 (CAN-) - Body ground or other terminals Always 1 MΩ or higher

    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.

    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.

      Result
      Display (DTC Output) Proceed to
      U0100 A
      No DTC B

    B

    REPLACE TCM Click here

    A

    REPLACE ECM Click here