CAN COMMUNICATION 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 circuit of ECM

  • ECM

  • ECM main wire or connector

WIRING DIAGRAM

A005VGQE01
A005THSE01

INSPECTION PROCEDURE

Note

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

Tech Tips

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

PROCEDURE


  1. DISCONNECT CABLE FROM BATTERY NEGATIVE BATTERY TERMINAL


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

      CAUTION:

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

      Note


      • w/ Navigation System (for HDD):

        After the ignition switch is turned off, the HDD navigation system requires approximately a minute to record various types of memory and settings. As a result, after turning the ignition switch off, wait a minute or more before disconnecting the cable from the negative (-) battery terminal.

      • 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)

    A005SMFE02
    Text in Illustration
    *1

    Front view of wire harness connector

    (to ECM)
    *2 for 1AZ-FE
    *3 except 1AZ-FE

    1. Disconnect the A40 ECM connector.

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

      Standard Resistance
      for 1AZ-FE
      Tester Connection Switch Condition Specified Condition
      A40-5 (CANP) - A40-4 (CANN) Ignition switch off 108 to 132 Ω
      except 1AZ-FE
      Tester Connection Switch Condition Specified Condition
      A40-6 (CANP) - A40-7 (CANN) Ignition switch off 108 to 132 Ω

    NG

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

    OK

  3. CHECK HARNESS AND CONNECTOR


    1. Connect the cable to the negative (-) battery terminal.

      Note

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

    2. Disconnect the A40 and B39 ECM connectors.

      A005V9HE02

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

      Standard Resistance
      for 1AZ-FE
      Tester Connection Condition Specified Condition
      A40-32 (EC) - Body ground Always Below 1 Ω
      B39-43 (ME01) - Body ground Always Below 1 Ω
      B39-44 (E02) - Body ground Always Below 1 Ω
      B39-45 (E01) - Body ground Always Below 1 Ω
      B39-104 (E1) - Body ground Always Below 1 Ω
      except 1AZ-FE
      Tester Connection Condition Specified Condition
      A40-32 (EC) - Body ground Always Below 1 Ω
      B39-41 (E04) - Body ground Always Below 1 Ω
      B39-44 (ME01) - Body ground Always Below 1 Ω
      B39-45 (E02) - Body ground Always Below 1 Ω
      B39-46 (E01) - Body ground Always Below 1 Ω
      B39-81 (E03) - Body ground Always Below 1 Ω
      B39-105 (E1) - Body ground Always Below 1 Ω

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

      Standard Voltage
      for 1AZ-FE
      Tester Connection Switch Condition Specified Condition
      A40-3 (+BM) - Body ground Always 11 to 14 V
      A40-20 (BATT) - Body ground Always 11 to 14 V
      A40-2 (+B) - Body ground Battery positive (+) voltage applied to terminal A40-44 (MREL) 11 to 14 V
      except 1AZ-FE
      Tester Connection Switch Condition Specified Condition
      A40-3 (+BM) - Body ground Always 11 to 14 V
      A40-20 (BATT) - Body ground Always 11 to 14 V
      A40-1 (+B2) - Body ground Battery positive (+) voltage applied to terminal A40-44 (MREL) 11 to 14 V
      A40-2 (+B) - Body ground 11 to 14 V
      Text in Illustration
      *1

      Front view of wire harness connector

      (to ECM)

      		 *3 except 1AZ-FE
      *2 for 1AZ-FE - -

      Tech Tips

      *: ECM replacement procedure:



    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM*