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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Engine Mechanical >> Starter >> Stop And Start System - Diagnostic Codes (2 Of 3) >> Stop And Start System >> DTC P30DF-62: Backup Boost Converter Circuit Board (Thermistor) Signal Compare Failure; DTC P30EF-4B: Backup Boost Converter Circuit Board Over Temperature; DTC P323A-00: Backup Boost Converter "A"; DTC P323A-16: Backup Boost Converter "A" Circuit Voltage Below Threshold; DTC P323A-A2: Backup Boost Converter "A" System Voltage Low; DTC P323B-29: Backup Boost Converter "A" Control Circuit Signal Invalid; DTC P323B-38: Backup Boost Converter "A" Control Circuit Signal Cycle Invalid [12/2019 - 10/2022] >> Procedure

DTC P30DF-62: Backup Boost Converter Circuit Board (Thermistor) Signal Compare Failure; DTC P30EF-4B: Backup Boost Converter Circuit Board Over Temperature; DTC P323A-00: Backup Boost Converter "A"; DTC P323A-16: Backup Boost Converter "A" Circuit Voltage Below Threshold; DTC P323A-A2: Backup Boost Converter "A" System Voltage Low; DTC P323B-29: Backup Boost Converter "A" Control Circuit Signal Invalid; DTC P323B-38: Backup Boost Converter "A" Control Circuit Signal Cycle Invalid [12/2019 - 10/2022]: Procedure

  1. CHECK HARNESS AND CONNECTOR (BIN1 AND BIN2 TERMINALS POWER SOURCE CIRCUIT) 
    GTY933968Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Engine Stop and Start ECU)
    1. Disconnect the engine stop and start ECU connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A33-1 (BIN2) - Body ground Always 9.5 to 14 V
      A33-3 (BIN1) - Body ground Always 9.5 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE STOP AND START ECU - BATTERY) 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL POWER SOURCE CIRCUIT) 
    GTY897204Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Engine Stop and Start ECU)
    1. Disconnect the engine stop and start ECU connector.
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      H66-21 (IG1) - Body ground Ignition switch ON 9.5 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE STOP AND START ECU - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (IG1-NO. 1 RELAY)) 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - BODY GROUND) 
    1. Disconnect the engine stop and start ECU connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A34-6 (DGND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - EACH ECU OR SENSOR) 
    1. Disconnect the engine stop and start ECU connector.
    2. Remove the FOG FR relay from the No. 1 engine room relay block and No. 1 junction block assembly. (w/ Front Fog Light)
    3. Disconnect the integration control sub-assembly connector. (w/ 12.3 Inch Display)
    4. Disconnect the tire pressure warning ECU and receiver connector.
    5. Disconnect the navigation ECU connector. (w/ Navigation System)
    6. Disconnect the meter mirror assembly connector. (w/ Headup Display)
    7. Disconnect the radio and display receiver assembly connector. (w/o 12.3 Inch Display)
    8. Disconnect the radio receiver assembly connector. (w/ 12.3 Inch Display)
    9. Disconnect the multi-display assembly connector. (w/ 12.3 Inch Display)
    10. Disconnect the television display assembly connector. (w/ Rear Seat Entertainment System)
    11. Disconnect the inner rear view mirror assembly connector. (w/ EC Mirror or Digital Inner Mirror)
    12. Disconnect the front door ambient light LH (front door trim board sub-assembly LH) connector. (w/ Ambient Illumination Light)
    13. Disconnect the front door ambient light RH (front door trim board sub-assembly RH) connector. (w/ Ambient Illumination Light)
    14. Disconnect the rear door ambient light LH (rear door trim board sub-assembly LH) connector. (w/ Ambient Illumination Light)
    15. Disconnect the rear door ambient light RH (rear door trim board sub-assembly RH) connector. (w/ Ambient Illumination Light)
    16. Disconnect the front passenger side tray illumination light (No. 1 instrument panel light sub-assembly) connector. (w/ Ambient Illumination Light)
    17. Disconnect the center tray illumination light (No. 1 instrument panel light sub-assembly) connector. (w/ Ambient Illumination Light)
    18. Disconnect the air conditioning control assembly connector.
    19. Disconnect the central gateway ECU (network gateway ECU) connector.
    20. Disconnect the millimeter wave radar sensor assembly connector.
    21. Disconnect the clearance warning ECU assembly connector.
    22. Disconnect the blind spot monitor sensor LH connector.
    23. Disconnect the blind spot monitor sensor RH connector.
    24. Disconnect the No. 2 air conditioning control assembly connector.
    25. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H66-2 (B41) - 2 (FOG FR relay)*1 Always Below 1 Ω
      H66-2 (B41) - 5 (FOG FR relay)*1 Always Below 1 Ω
      H66-2 (B41) - H8-1 (B)*3 Always Below 1 Ω
      H66-2 (B41) - M51-7 (+B) Always Below 1 Ω
      H66-2 (B41) - H18-10 (+B)*2 Always Below 1 Ω
      H66-2 (B41) - H31-2 (B)*5 Always Below 1 Ω
      H66-12 (B42) - H1-4 (+B1)*4 Always Below 1 Ω
      H66-12 (B42) - H4-4 (+B1)*3 Always Below 1 Ω
      H66-11 (B43) - H7-12 (B)*3 Always Below 1 Ω
      H66-11 (B43) - R16-1 (+B)*6 Always Below 1 Ω
      H66-11 (B43) - R1-6 (B)*7 Always Below 1 Ω
      H66-11 (B43) - R1-6 (+B)*8 Always Below 1 Ω
      H66-11 (B43) -J26-2 (+)*10 Always Below 1 Ω
      H66-11 (B43) -J10-2 (+)*10 Always Below 1 Ω
      H66-11 (B43) -K10-2 (+)*10 Always Below 1 Ω
      H66-11 (B43) -K5-2 (+)*10 Always Below 1 Ω
      H66-11 (B43) -H69-2 (ILL+)*10 Always Below 1 Ω
      H66-11 (B43) -H68-2 (ILL+)*10 Always Below 1 Ω
      H66-3 (IG41) - H8-4 (IG+)*3 Always Below 1 Ω
      H66-3 (IG41) - R1-1 (IG)*9 Always Below 1 Ω
      H66-3 (IG41) - M51-1 (IG) Always Below 1 Ω
      H66-3 (IG41) - H31-1 (IG+)*5 Always Below 1 Ω
      H66-3 (IG41) - H27-4 (IG+)*3 Always Below 1 Ω
      H66-3 (IG41) - H27-6 (IG+)*4 Always Below 1 Ω
      H66-3 (IG41) - H59-11 (IG1) Always Below 1 Ω
      H66-3 (IG41) - B6-8 (IGB) Always Below 1 Ω
      H66-3 (IG41) - H46-1 (IG) Always Below 1 Ω
      H66-3 (IG41) - M43-5 (BLB) Always Below 1 Ω
      H66-3 (IG41) - M2-5 (BRB) Always Below 1 Ω
      H66-3 (IG41) - T2-9 (IG) Always Below 1 Ω
      H66-2 (B41) or 2 (FOG FR relay)*1 - Body ground and other terminals Always 10 kΩ or higher
      H66-2 (B41) or 5 (FOG FR relay)*1 - Body ground and other terminals Always 10 kΩ or higher
      H66-2 (B41) or H8-1 (B)*3 - Body ground and other terminals Always 10 kΩ or higher
      H66-2 (B41) or M51-7 (+B) - Body ground and other terminals Always 10 kΩ or higher
      H66-2 (B41) or H18-10 (+B)*2 - Body ground and other terminals Always 10 kΩ or higher
      H66-2 (B41) or H31-2 (B)*5 - Body ground and other terminals Always 10 kΩ or higher
      H66-12 (B42) or H1-4 (+B1)*4 - Body ground and other terminals Always 10 kΩ or higher
      H66-12 (B42) or H4-4 (+B1)*3 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or H7-12 (B)*3 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or R16-1 (+B)*6 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or R1-6 (B)*7 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or R1-6 (+B)*8 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or J26-2 (+)*10 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or J10-2 (+)*10 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or K10-2 (+)*10 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or K5-2 (+)*10 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or H69-2 (ILL+)*10 - Body ground and other terminals Always 10 kΩ or higher
      H66-11 (B43) or H68-2 (ILL+)*10 - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or H8-4 (IG+)*3 - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or R1-1 (IG)*9 - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or M51-1 (IG) - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or H31-1 (IG)*5 - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or H27-4 (IG+)*3 - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or H27-6 (IG+)*4 - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or H59-11 (IG1) - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or B6-8 (IGB) - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or H46-1 (IG) - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or M43-5 (BLB) - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or M2-5 (BRB) - Body ground and other terminals Always 10 kΩ or higher
      H66-3 (IG41) or T2-9 (IG) - Body ground and other terminals Always 10 kΩ or higher
      1. *1: w/ Front Fog Light
      2. *2: w/ Navigation System
      3. *3: w/ 12.3 Inch Display
      4. *4: w/o 12.3 Inch Display
      5. *5: w/ Headup Display
      6. *6: w/ Rear Seat Entertainment System
      7. *7: w/ Digital Inner Mirror
      8. *8: w/ EC Mirror
      9. *9: w/ EC Mirror or Digital Inner Mirror
      10. *10: w/ Ambient Illumination Light

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ENGINE STOP AND START ECU. Refer to  REMOVAL [12/2019 - 10/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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