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 in this communication, the TCM sets the DTC.

DTC Code DTC Detection Condition Trouble Area
U0100

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


  • Engine switch on (IG)

  • Battery voltage is 10.5 V or more

  • No communication between the ECM and TCM

  • Harness and connector

  • ECM

  • TCM

WIRING DIAGRAM

A0162OGE06

INSPECTION PROCEDURE

Tech Tips


  • If CAN communication malfunctions, the TCM cannot receive the current data from the ECM. In this case, the freeze frame data output from the TCM is not 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 checked using the CAN Bus Check function on the intelligent tester Click here.

PROCEDURE


  1. CHECK DTC OUTPUT (IN ADDITION TO DTC U0100)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the intelligent tester on.

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

    5. Read the DTCs using the intelligent tester.

      Result
      Display (DTC Output) Proceed to
      Only U0100 is output A
      U0100 and other DTCs are output B

      Tech Tips

      If any other codes besides U0100 are output, perform troubleshooting for those DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. INSPECT TCM (POWER SOURCE, BODY GROUND)


    1. A0161TWE21

      Disconnect the 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 Switch Condition Specified Condition
      A58-5 (+B) - A58-2 (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
      E58-2 (E1) - Body ground Always Below 1 Ω

    NG

    CHECK TCM POWER SOURCE CIRCUIT Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM)


    1. A0161NTE03

      Disconnect the ECM connector.

    2. Disconnect the TCM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A6-10 (CAN+) - A58-21 (CAN+) Always Below 1 Ω
      A6-9 (CAN-) - A58-13 (CAN-) Always Below 1 Ω
      A6-10 (CAN+) or A58-21 (CAN+) - Body ground Always 10 kΩ or higher
      A6-9 (CAN-) or A58-13 (CAN-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK IF DTC RECURS


    1. Clear the DTCs Click here.

    2. Replace the TCM Click here.

      Tech Tips

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

    3. Start the engine.

    4. Read the DTCs.

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

    B

    REPLACE ECM Click here

    A

  5. REPLACE TCM


    1. Replace the TCM Click here.


    NEXT

    PERFORM A/T CODE REGISTRATION Click here