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DTC U0104: Lost Communication with Driving Support ECU [08/2013 - ]: Procedure

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
  1. RECONFIRM DTC OUTPUT 
    1. Reconfirm DTCs.

      HINT: 

      If DTC U1002 is output from PM1 Gateway of the power management control ECU, this indicates a sub bus 11 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 11.

      Result

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

    B → See step   5 

    A: Go to next step 

  2. CHECK FOR OPEN IN CAN BUS LINES (DRIVING SUPPORT ECU ASSEMBLY BRANCH LINE) 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Disconnect the H75 driving support ECU assembly connector.
      GTY405336Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    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 (-) auxiliary battery terminal 54 to 69 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Driving Support ECU Assembly)

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

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY405335Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      H75-25 (GND) - Body ground Cable disconnected from negative (-) auxiliary battery terminal Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Driving Support ECU Assembly)
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Measure the voltage according to the value(s) in the table below.
      GTY405401Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      H75-30 (B) - Body ground Power switch on (IG) 11 to 14 V
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Driving Support ECU Assembly)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) 

    OK → See step   4 

  4. REPLACE DRIVING SUPPORT ECU ASSEMBLY. Refer to  REMOVAL [08/2013 - ] 
  5. GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC. Refer to  DTC U1002: Lost Communication with Gateway Module [08/2013 - ]  
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