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Home >> Lexus >> 2022 >> LX 600 Base >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Stop And Start System - Diagnostic Codes (2 Of 2) & Circuit Tests >> Stop And Start System >> DTC P323A-19: Backup Boost Converter "A" Circuit Current Above Threshold [12/2021 - 10/2023] >> Procedure
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DTC P323A-19: Backup Boost Converter "A" Circuit Current Above Threshold [12/2021 - 10/2023]: Procedure

  1. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - BBC NO. 1, BBC NO. 2 FUSES) 

    Pre-procedure1

    • Disconnect the engine stop and start ECU connector.
    • Remove the BBC NO. 1 and BBC NO. 2 fuses from the NO. 2 engine room relay block and junction block assembly.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      B37-1 (BIN2) - BBC NO. 2 fuse terminal 2 Always Below 1 Ω
      B37-3 (BIN1) - BBC NO. 1 fuse terminal 2 Always Below 1 Ω
      B37-1 (BIN2) - Body ground Always 10 kΩ or higher
      BBC NO. 2 fuse terminal 2 - Body ground Always 10 kΩ or higher
      B37-3 (BIN1) - Body ground Always 10 kΩ or higher
      BBC NO. 1 fuse terminal 2 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - EACH ECU OR SENSOR) 

    Pre-procedure1

    • Disconnect the engine stop and start ECU connector.
    • Disconnect the tire pressure warning ECU and receiver connector.
    • Disconnect the meter mirror sub-assembly connector.
    • Disconnect the millimeter wave radar sensor assembly connector.
    • Disconnect the No. 2 air conditioning control assembly connector.
    • Disconnect the clearance warning ECU assembly connector.
    • Disconnect the integration control sub-assembly connector.
    • Disconnect the No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
    • Disconnect the inner rear view mirror assembly connector.
    • Remove the DOME CUT relay from the No. 1 luggage room relay block and junction block assembly.
    • Disconnect the cooler control switch assembly connector.
    • Disconnect the room light control relay connector.
    • Disconnect the spot light assembly RH connector. (for 4 Seater)
    • Disconnect the spot light assembly LH connector. (for 4 Seater)
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I57-3 (IG41) - T11-1 (IG) Always Below 1 Ω
      I57-3 (IG41) - I17-1 (IG) Always Below 1 Ω
      I57-3 (IG41) - A10-8 (IGB) Always Below 1 Ω
      I57-3 (IG41) - Q52-10 (IG) Always Below 1 Ω
      I57-3 (IG41) - I58-1 (IG) Always Below 1 Ω
      I57-3 (IG41) - I199-20 (IG+) Always Below 1 Ω
      I57-3 (IG41) - I201-8 (IG) Always Below 1 Ω
      I57-2 (B41) - T11-7 (+B) Always Below 1 Ω
      I57-2 (B41) - B19-14 (+BI1) Always Below 1 Ω
      I57-2 (B41) - d22-6 (+B) Always Below 1 Ω
      I57-2 (B41) - I199-40 (B) Always Below 1 Ω
      I57-11 (B43) - DOME CUT relay terminal 5 Always Below 1 Ω
      I57-11 (B43) - I17-2 (B) Always Below 1 Ω
      I57-11 (B43) - Q116-12 (B) Always Below 1 Ω
      I57-11 (B43) - I212-1 (+B) Always Below 1 Ω
      I57-11 (B43) - d32-2 (B)* Always Below 1 Ω
      I57-11 (B43) - d33-2 (B)* Always Below 1 Ω
      I57-3 (IG41) - Body ground Always 10 kΩ or higher
      I57-2 (B41) - Body ground Always 10 kΩ or higher
      I57-11 (B43) - Body ground Always 10 kΩ or higher

      *: for 4 Seater

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK ENGINE STOP AND START ECU 

    Pre-procedure1

    • Disconnect the engine stop and start ECU connectors.
      GTY1066494Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Engine Stop and Start ECU)
      - -
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I57-3 (IG41) - B38-6 (DGND) Always 10 kΩ or higher
      I57-2 (B41) - B38-6 (DGND) Always 10 kΩ or higher
      I57-12 (B42) - B38-6 (DGND) Always 10 kΩ or higher
      I57-11 (B43) - B38-6 (DGND) Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPLACE ENGINE STOP AND START ECU. Refer to  REMOVAL [12/2021 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK VEHICLE CONDITION (B41, B42, B43 AND IG41 CIRCUIT) 
    1. Check that additional devices installed to the vehicle (aftermarket audio system, etc.) are not connected to the B41, B42, B43 or IG41 terminal circuit of the engine stop and start ECU.

      Result

      Result Proceed to
      Load from an additional device installed to the vehicle (aftermarket audio system, etc.) is not applied. A
      Load from an additional device installed to the vehicle (aftermarket audio system, etc.) is applied. B

    Result: 

    TROUBLESHOOT ECUS CONNECTED TO TERMINALS B41, B42, B43 AND IG41 

    Result: 

    END (REMOVE ADDITIONAL DEVICE)