SFI SYSTEM (w/ Electronic Throttle Control System), Diagnostic DTC:U0101, U0129

DTC Code DTC Name
U0101 Lost Communication with TCM
U0129 Lost Communication with Skid Control ECU

DESCRIPTION

The ECM intercommunicates with the transmission control ECU, skid control ECU and other systems through the Controller Area Network (CAN).

If there is a problem in this intercommunication, the ECM illuminates the MIL and stores a DTC.

DTC No. DTC Detection Condition Trouble Area
U0101

  • Following conditions are met for 0.7 seconds or more (1 trip detection logic):


    1. Ignition switch ON

    2. Battery voltage 10.8 V or more

    3. No intercommunication between ECM and transmission control ECU

  • ECM

  • Transmission control ECU

  • Open or short in ECM and transmission control ECU circuit
U0129

  • Following conditions are met for 2.0 seconds or more (1 trip detection logic):


    1. Ignition switch ON

    2. Battery voltage 10.8 V or more

    3. No intercommunication between ECM and skid control ECU

  • ECM

  • Skid control ECU

  • Open or short in ECM and skid control ECU circuit

WIRING DIAGRAM

A01370YE01
A0136KLE01

INSPECTION PROCEDURE

Tech Tips

If the CAN communication malfunctions, the transmission control ECU and/or the skid control ECU cannot receive the current data from the ECM. In this case, the freeze frame data output from the transmission control ECU and/or the skid control ECU have not been updated so it will not be useful information for the inspection procedure. However, reading the Data List as the first step of troubleshooting is effective for finding malfunctions.

Note

After replacing the ECM, perform electronic throttle learning Click here.

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

PROCEDURE


  1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC U0101 AND/OR U0129)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester on.

    3. Enter the following menus: Powertrain / Engine and ECT / DTC.

    4. Read DTCs.

      Result
      Result Proceed to
      U0101 (w/o VSC) A
      U0101 (w/ VSC) B
      U0129 B
      U0101 and/or U0129 and other DTCs C

      Tech Tips

      If any DTCs other than U0101 and/or U0129 are output, troubleshoot those DTCs first.


    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    C

    GO TO DTC CHART Click here

    A

  2. INSPECT TRANSMISSION CONTROL ECU

    A0137AGE02
    Text in Illustration
    *a

    Front view of wire harness connector

    (to Transmission Control ECU)

    1. Disconnect the transmission control ECU 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
      A27-1 (+B) - Body ground Ignition switch ON 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A27-6 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - TRANSMISSION CONTROL ECU, TRANSMISSION CONTROL ECU - BODY GROUND)

    OK

  3. CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL ECU - ECM)


    1. Disconnect the A28 transmission control ECU connector.

    2. Disconnect the B26 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A28-1 (CAN+) - B26-28 (CAN+) Always Below 1 Ω
      A28-2 (CAN-) - B26-36 (CAN-) Always Below 1 Ω
      A28-1 (CAN+) or B26-28 (CAN+) - Body ground Always 10 kΩ or higher
      A28-2 (CAN-) or B26-36 (CAN-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE ECM


    1. Replace the ECM Click here.

      Note

      After replacing the ECM, perform electronic throttle learning Click here.


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester on.

    3. Enter the following menus: Powertrain / Engine and ECT / DTC.

    4. Read DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC U0101 is output B

    B

    REPLACE TRANSMISSION CONTROL ECU Click here

    A

    END