AUTOMATIC TRANSAXLE 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

  • No communication between the ECM and TCM

  • Harness and connector

  • ECM

  • TCM

Comes on

DTC stored

WIRING DIAGRAM

C279427E01

CAUTION / NOTICE / HINT

Note:

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

Click here

Tip:

  • 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 with Central Gateway ECU:

    Click hereClick here

    for RHD with Central Gateway ECU:

    Click hereClick hereClick here

    for LHD without Central Gateway ECU:

    Click hereClick here

    for RHD without Central Gateway ECU:

    Click hereClick here

PROCEDURE

  1. CHECK ECM TERMINAL VOLTAGE (+B AND +B2 TERMINALS)

    1. C197708C06

      *a

      Front 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

      Switch Condition

      Specified Condition

      A61-1 (+B) - Body ground

      Ignition switch ON

      11 to 14 V

      A61-20 (+B2) - Body ground

      Ignition switch ON

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    GO TO ECM POWER SOURCE CIRCUIT

    for 2AD-FTV:

    Click here

    for 2AD-FHV:

    Click here

    OK

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

    1. C197707C07

      *a

      Front 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

      B76-109 (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 B76 ECM connector.

    2. Disconnect the B79 TCM connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      B76-40 (CAN+) - B79-6 (CAN+)

      Always

      Below 1 Ω

      B76-63 (CAN-) - B79-7 (CAN-)

      Always

      Below 1 Ω

      B76-40 (CAN+) or B79-6 (CAN+) - Body ground or other terminals

      Always

      10 kΩ or higher

      B76-63 (CAN-) or B79-7 (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 IF DTC OUTPUT RECURS (DTC U0100)

    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

      U0100 is output

      A

      DTCs are not output

      B
    A

    REPLACE ECM

    for 2AD-FHV:

    Click here

    for 2AD-FTV:

    Click here

    B

    END