CAN COMMUNICATION SYSTEM (for LHD), Diagnostic DTC:U0140, U0142

DTC Code DTC Name
U0140 Lost Communication with Main Body ECU
U0142 Lost Communication with Main Body ECU

DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U0140 There is no communication from the main body ECU (multiplex network body ECU).

  • Power source or inside of main body ECU (multiplex network body ECU)

  • Main body ECU (multiplex network body ECU) CAN branch wire or connector

  • Main body ECU (multiplex network body ECU)

  • Cowl side junction block LH
U0142

WIRING DIAGRAM

A01FI9UE02

INSPECTION PROCEDURE

Note


  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output Click here.

  • Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • 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.

  • If the main body ECU (multiplex network body ECU) is replaced, refer to the Service Bulletin.

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

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • DTC check procedure: Turn the engine switch on (IG) and turn the blind spot monitor main switch on, and then wait 11.6 seconds or more.

  • After the repair, perform CAN Bus Check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.

Tech Tips


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

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE


  1. RECONFIRM DTC OUTPUT


    1. Reconfirm DTCs.

      Tech Tips

      If DTC U1002 is output from Gateway of the main body ECU (multiplex network body ECU), this indicates a sub bus 1 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 1.

      Result
      Result Proceed to
      DTC U1002 is not output from main body ECU (multiplex network body ECU). A
      DTC U1002 is output from main body ECU (multiplex network body ECU). B

    B

    GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

    A

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


    1. A01FGC5E01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to Main Body ECU [Multiplex Network Body ECU])

      Disconnect the cable from the negative (-) battery terminal.

    2. Disconnect the main body ECU (multiplex network body ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      N13-9 (CANP) - N13-10 (CANN) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

    NG

    REPAIR OR REPLACE MAIN BODY ECU CAN MAIN WIRE OR CONNECTOR (CANP, CANN)

    OK

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


    1. A01FGMTE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Main Body ECU [Multiplex Network Body ECU])

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

      Note

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

    2. Remove the main body ECU (multiplex network body ECU) Click here.

    3. Reconnect the 5A, 5B, 5D and 5E cowl side junction block LH connectors.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A-30 (BECU) - Body ground Always 11 to 14 V
      A-31 (ALTB) - Body ground Always 11 to 14 V
      A-29 (ACC) - Body ground Engine switch on (ACC) 11 to 14 V
      A-32 (IG) - Body ground Engine switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A-11 (GND1) - Body ground Always Below 1 Ω

    NG

    CHECK HARNESS AND CONNECTOR (COWL SIDE JUNCTION BLOCK LH - BATTERY AND BODY GROUND) Click here

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

  4. CHECK HARNESS AND CONNECTOR (COWL SIDE JUNCTION BLOCK LH - BATTERY AND BODY GROUND)


    1. Disconnect the cowl side junction block LH connectors.

      A01FHPXE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Cowl Side Junction Block LH)

      		 - -

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      5D-32 - Body ground Always 11 to 14 V
      5E-1 - Body ground Always 11 to 14 V
      5B-19 - Body ground Engine switch on (ACC) 11 to 14 V
      5A-35 - Body ground Engine switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      5B-1 - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE COWL SIDE JUNCTION BLOCK LH Click here