CAN COMMUNICATION SYSTEM, Diagnostic DTC:U0104

DTC Code DTC Name
U0104 Lost Communication with Driving Support ECU

DESCRIPTION

DTC No. DTC Detection Condition Trouble Area
U0104 No communication from the driving support ECU assembly continues.

  • Driving support ECU assembly branch line or connector

  • Power source circuit of driving support ECU assembly

  • Driving support ECU assembly ground circuit

  • Driving support ECU assembly

Tech Tips

This diagnosis procedure is for when DTC U0104 is output by the network gateway ECU (GTS display: Gateway).

WIRING DIAGRAM

A01G5PWE03

INSPECTION PROCEDURE

Note


  • 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 negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work Click here.

  • 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.

  • 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), wait at least 20 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 other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

  • 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 network gateway ECU, this indicates a sub bus 2 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 2.

      Result
      Result Proceed to
      U1002 is not output from network gateway ECU (GTS display: Gateway) A
      U1002 is output from network gateway ECU (GTS display: Gateway) B

    B

    GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

    A

  2. CHECK FOR OPEN IN CAN BUS LINES (DRIVING SUPPORT ECU ASSEMBLY BRANCH LINE)


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

    2. A01G7F0E11
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU Assembly)

      Disconnect the H75 driving support ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H75-39 (CA2H) - H75-17 (CA2L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

    NG

    REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY)

    OK

  3. CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)


    1. A01G7F0E12
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H75-25 (GND) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω

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

    3. A01G7F0E13
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      H75-30 (B) - Body ground Engine switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

    REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here