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 continues.

  • Driving support ECU branch wire or connector

  • Power source circuit of driving support ECU

  • Driving support ECU

Tech Tips

The diagnosis procedure is for when DTC U0104 is output by the power management control ECU (GTS display: PM1 Gateway).

WIRING DIAGRAM

A00417QE05
A0042YHE02

INSPECTION PROCEDURE

Note


  • Turn the power switch off before measuring the resistances between CAN main bus wires and between CAN main bus branch wires.

  • Turn the power switch off before inspecting CAN bus wires for a ground short.

  • After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.

  • Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

Tech Tips


  • Operating the power 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 V2 bus DTC U1002 is output from the power management control ECU (GTS display: PM1 Gateway), troubleshoot for U1002 and check for malfunctions in the V2 main bus circuit.

      Result
      Result Proceed to
      U1002 is not output from power management control ECU (GTS display: PM1 Gateway) A
      U1002 is output from power management control ECU (GTS display: PM1 Gateway) B

    B

    GO TO CIRCUITS INDICATED BY OUTPUT DTCS Click here

    A

  2. CHECK FOR OPEN IN CAN BUS WIRES (DRIVING SUPPORT ECU BRANCH WIRE)


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

    2. Disconnect the L54 driving support ECU connector.

    3. A0042FJE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L54-39 (CA2H) - L54-17 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

    NG

    REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (DRIVING SUPPORT ECU BRANCH WIRE)

    OK

  3. CHECK HARNESS AND CONNECTOR (GROUND TERMINAL)


    1. A0042FJE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L54-25 (GND) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω

    NG

    HARNESS OR CONNECTOR (GROUND CIRCUIT)

    OK

  4. CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)


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

    2. A0042FJE04
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Driving Support ECU)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      L54-30 (B) - Body ground Power switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

    REPLACE DRIVING SUPPORT ECU Click here