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Inspection Procedure

  1. CHECK WIRE HARNESS (CERTIFICATION ECU - BATTERY AND BODY GROUND) 
    1. Disconnect the U28 ECU connector.
    2. Measure the resistance and voltage of the wire harness side connector.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      U28-1 (+B1) - Body ground 10 to 14 V

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      U28-17 (E) - Body ground Below 1 Ω
    Fig 1: Identifying Certification ECU Connector Terminals
    G05301207Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: Go to next step 

  2. CHECK RESISTANCE OF COMMUNICATION LINE 
    Fig 2: Identifying Certification ECU, Network Gateway ECU And Multiplex Network Door ECU Connector Terminals
    G05301208Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the a7, K66, M4 and U28 ECU connectors.
    2. Measure the resistance of the wire harness side connectors.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      U28-27 (MPX1) - M4-8 (MPX1) Below 1 Ω
      U28-27 (MPX1) - a7-1 (MPX1) Below 1 Ω
      U28-28 (MPX2) - K66-12 (MPD2) Below 1 Ω

      Result 

      RESULT CHART

      Result Proceed to
      Both are OK A
      One or two is / are OK B
      Both are NG C

    B: REPLACE CERTIFICATION ECU AND WIRE HARNESS CONNECTOR 

    C: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    A: REPLACE CERTIFICATION ECU 

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