CAN COMMUNICATION SYSTEM(for LHD with Entry and Start System), Diagnostic DTC:U0100

DTC Code DTC Name
U0100 Lost Communication with ECM / PCM "A"

DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U0100 There is no communication from the ECM.

  • Power source or inside ECM

  • ECM main wire or connector

  • ECM

WIRING DIAGRAM

A01XCIRE01
for 1GR-FE and Manual Transmission System
*1 No. 1 Junction Connector
*2 from Battery
*3 from EFI Relay
*4 to EFI Relay
A01XM1ZE01
for 1KD-FTV
*a No. 1 Junction Connector
*b from Battery
*c from EFI Relay
*d to EFI Relay

CAUTION / NOTICE / HINT

Note

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

Tech Tips

Operating the engine switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

PROCEDURE


  1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL


    1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and the CAN branch wire.

      CAUTION:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the airbag system.

      Note


      • After turning the engine switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.

      • When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.


    NEXT

  2. CHECK FOR OPEN IN CAN BUS MAIN WIRE (ECM MAIN WIRE)


    1. Disconnect the G56*1 or G57*2 ECM connector.


      • *1: for 1GR-FE and Manual Transmission System

      • *2: for 1KD-FTV

      A01XM0CE01
      Text in Illustration
      *A for 1GR-FE and Manual Transmission System *B for 1KD-FTV
      *a

      Front view of wire harness connector

      (to ECM)

      		 - -

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

      Standard Resistance
      for 1GR-FE and Manual Transmission System
      Tester Connection Switch Condition Specified Condition
      G56-34 (CANP) - G56-33 (CANN) Engine switch off 108 to 132 Ω
      for 1KD-FTV
      Tester Connection Switch Condition Specified Condition
      G57-20 (CANP) - G57-21 (CANN) Engine switch off 108 to 132 Ω

    NG

    REPAIR OR REPLACE ECM MAIN WIRE OR CONNECTOR (CANP, CANN)

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - BATTERY AND BODY GROUND)

    Note

    When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.


    1. for 1GR-FE and Manual Transmission System:


      1. Disconnect the C36, C37 and G55 ECM connectors.

        B001DI3E01
        Text in Illustration
        *a

        Front view of wire harness connector

        (to ECM)

        		 - -

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        C36-12 (E1) - Body ground Always Below 1 Ω
        C37-14 (E01) - Body ground Always Below 1 Ω
        C37-15 (E02) - Body ground Always Below 1 Ω
        C37-10 (ME01) - Body ground Always Below 1 Ω
        G55-12 (EC) - Body ground Always Below 1 Ω

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        G55-24 (BATT) - Body ground Always 11 to 14 V
        G55-23 (+B2) - Body ground Battery positive (+) voltage applied to terminal G55-9 (MREL) 11 to 14 V
        G55-22 (+B) - Body ground Battery positive (+) voltage applied to terminal G55-9 (MREL) 11 to 14 V

    2. for 1KD-FTV:


      1. Disconnect the C93, G57 and G58 ECM connectors.

        B001FNFE01
        Text in Illustration
        *a

        Front view of wire harness connector

        (to ECM)

        		 - -

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        C93-1 (E1) - Body ground Always Below 1 Ω
        C93-12 (E01) - Body ground Always Below 1 Ω
        C93-13 (E02) - Body ground Always Below 1 Ω
        C93-8 (ME01) - Body ground Always Below 1 Ω
        G57-11 (EC) - Body ground Always Below 1 Ω

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        G57-23 (BATT) - Body ground Always 11 to 14 V
        G57-17 (+B2) - Body ground Battery positive (+) voltage applied to terminal G58-11 (MREL) 11 to 14 V
        G57-24 (+B) - Body ground Battery positive (+) voltage applied to terminal G58-11 (MREL) 11 to 14 V
      Result
      Result Proceed to
      OK (for 1GR-FE) A
      OK (for 1KD-FTV) B
      NG C

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR