STOP AND START SYSTEM, Diagnostic DTC:P323B

DTC Code DTC Name
P323B Backup Boost Converter

DESCRIPTION

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DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate Memory
P323B Backup Boost Converter

Any of the following conditions is met for 1 second or more (1 trip detection logic):


  • Backup boost converter malfunction is detected

  • Engine stop and start ECU thermistor temperature is 128°C (262.4°F) or higher

  • Difference in temperature between thermistor 1 and thermistor 2 of the engine stop and start ECU is 40°C (104°F) or higher

  • B41, B42, B43 voltage is 6.0 V or less, backup boost converter is not overheating and backup boost converter output overcurrent is not detected

  • IG41 voltage is 6.0 V or less and backup boost converter output overcurrent is not detected

  • Engine stop and start ECU

  • Wire harness or connector

  • Battery

  • BBC NO. 1 fuse

  • BBC NO. 2 fuse

 Blinks DTC stored

CONFIRMATION DRIVING PATTERN

Tech Tips

DTCs for the stop and start system are not cleared even if the malfunction has been repaired. After repairing the malfunction, be sure to clear the DTCs.

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  1. Tech Tips


    • If the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 60 minutes until refresh charge is completed and stop and start control operation is permitted.

    • Allow the engine to idle for 3 minutes after the engine warms up and check that the engine speed is within 50 rpm of the target idle speed.

    CONFIRMATION AFTER TROUBLESHOOTING


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG) and turn the GTS on.

    3. Clear the DTCs.

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      Powertrain > Stop and Start > Clear DTCs

    4. Start the engine and warm it up.

    5. Drive the vehicle at 7 km/h (4.3 mph) or more.

      CAUTION:

      When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

    6. Depress the brake pedal and stop the vehicle.

    7. Keep the engine stopped by stop and start control for 1 second or more. (Keep the shift lever in D.)

    8. Release the brake pedal with the shift lever in D to start the engine.

      Tech Tips

      If the engine cranks slowly when the engine is restarted, it can be determined that the battery voltage is low.

    9. Check that DTCs are not output.

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      Powertrain > Stop and Start > Trouble Codes

  2. STOP AND START SYSTEM OPERATION CHECK

    Tech Tips

    If the cable is disconnected from the negative (-) battery terminal, stop and start control is prohibited until refresh charge is completed. In this case, drive the vehicle approximately 5 to 60 minutes until refresh charge is completed and stop and start control operation is permitted.


    1. Start the engine and warm it up.

    2. Turn the air conditioning system off.

    3. Drive the vehicle at 7 km/h (4.3 mph) or more.

      CAUTION:

      When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    4. Depress the brake pedal and stop the vehicle.

    5. Allow the engine to stop by stop and start control. (Keep the shift lever in D.)

    6. Release the brake pedal with the shift lever in D to start the engine.

WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Note


  • Before replacing the engine stop and start ECU, read the number of starter operations and total number of engine starts and write it into a new engine stop and start ECU.

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  • After replacing the engine stop and start ECU or air conditioning amplifier assembly, reset and perform learning of the air conditioning information in the engine stop and start ECU.

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  • After replacing the engine stop and start ECU, airbag sensor assembly*1 or yaw rate and acceleration sensor*2, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.

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    • *1: for Optitron Meter Type

    • *2: for TFT Meter Type

  • Inspect the fuses for circuits related to this system before performing the following procedure.

Tech Tips

Using the GTS, read the freeze frame data before troubleshooting. System condition information is recorded as freeze frame data the moment a DTC is stored. This information can be useful when troubleshooting.

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PROCEDURE


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


    1. Disconnect the A65 engine stop and start ECU connector.

    2. Remove the BBC NO. 1 fuse from the No. 1 engine room relay block and No. 1 junction block assembly.

    3. Remove the BBC NO. 2 fuse from the No. 1 engine room relay block and No. 1 junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A65-1 (BIN2) - BBC NO. 2 fuse terminal 2 Always Below 1 Ω
      A65-3 (BIN1) - BBC NO. 1 fuse terminal 2 Always Below 1 Ω
      A65-1 (BIN2) - Body ground Always 10 kΩ or higher
      BBC NO. 2 fuse terminal 2 - Body ground Always 10 kΩ or higher
      A65-3 (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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU POWER SOURCE CIRCUIT)


    1. B005MYJC25
      *a

      Front view of wire harness connector:

      (to Engine Stop and Start ECU)

      Disconnect the engine stop and start ECU connectors.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A65-1 (BIN2) - Body ground Always 9.5 to 14 V
      A65-3 (BIN1) - Body ground Always 9.5 to 14 V

    3. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      J46-21 (IG1) - Body ground Engine switch on (IG) 9.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - BODY GROUND)


    1. Disconnect the A65 and A66 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
      A65-2 (GND2) - Body ground Always Below 1 Ω
      A65-8 (GND1) - Body ground Always Below 1 Ω
      A66-6 (DGND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the J46 engine stop and start ECU connector.

    2. Disconnect the S54 tire pressure warning ECU and receiver connector.*1

    3. Disconnect the R23 tire pressure warning ECU and receiver connector.*2

    4. Disconnect the N12 front door trim board sub-assembly LH (front door ambient illumination light LH) connector.*3

    5. Disconnect the M12 front door trim board sub-assembly RH (front door ambient illumination light RH) connector.*3

    6. Disconnect the Q6 rear door trim board sub-assembly LH (rear door ambient illumination light LH) connector.*3

    7. Disconnect the Q5 rear door trim board sub-assembly RH (rear door ambient illumination light RH) connector.*3

    8. Disconnect the J13 No. 1 interior illumination light assembly LH (footwell light LH) connector.

    9. Disconnect the J37 No. 1 interior illumination light assembly RH (footwell light RH) connector.

    10. Disconnect the J18 No. 1 interior illumination light assembly (front console light) connector.

    11. Disconnect the K10 interior illumination light sub-assembly (instrument panel ambient illumination light) connector.*4

    12. Disconnect the J50 radio receiver assembly connector.*5

    13. Disconnect the J52 radio receiver assembly connector.*6

    14. Disconnect the J56 multi-display assembly connector.*7

    15. Disconnect the J137 accessory meter assembly connector.*8

    16. Disconnect the g1 remote touch (remote operation board) connector.*5

    17. Disconnect the J59 Lexus display audio controller (remote operation board) connector.*6

    18. Disconnect the X2 blind spot monitor sensor LH connector.*9

    19. Disconnect the W2 blind spot monitor sensor RH connector.*9

    20. Disconnect the A70 millimeter wave radar sensor assembly connector.*10

    21. Disconnect the A72 driving support ECU assembly connector.*10

    22. Disconnect the J75 Network gateway ECU connector.

    23. Disconnect the U14 forward recognition camera connector.*10

    24. Disconnect the J73 parking assist ECU connector.*11

    25. Disconnect the J38 clearance warning ECU assembly connector.*12

    26. Disconnect the K1 meter mirror sub-assembly connector.*13

    27. Disconnect the 2C instrument panel junction block assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J46-2 (B41) - R23-7 (+B)*2 Always Below 1 Ω
      J46-2 (B41) - g1-1 (+B)*8 Always Below 1 Ω
      J46-2 (B41) - J73-2 (+B)*11 Always Below 1 Ω
      J46-2 (B41) - K1-1 (+B)*13 Always Below 1 Ω
      J46-2 (B41) - 2C-7 Always Below 1 Ω
      J46-12 (B42) - J50-17 (+B1)*5 Always Below 1 Ω
      J46-12 (B42) - J52-4 (+B1)*6 Always Below 1 Ω
      J46-11 (B43) - J56-12 (B)*7 Always Below 1 Ω
      J46-11 (B43) - J137-12 (B)*8 Always Below 1 Ω
      J46-11 (B43) - N12-1 (+)*3 Always Below 1 Ω
      J46-11 (B43) - M12-1 (+)*3 Always Below 1 Ω
      J46-11 (B43) - Q6-1 (+)*3 Always Below 1 Ω
      J46-11 (B43) - Q5-1 (+)*3 Always Below 1 Ω
      J46-11 (B43) - J13-2 (B) Always Below 1 Ω
      J46-11 (B43) - J37-2 (B) Always Below 1 Ω
      J46-11 (B43) - J18-2 (B) Always Below 1 Ω
      J46-11 (B43) - K10-2 (RRIL)*4 Always Below 1 Ω
      J46-3 (IG41) - S54-1 (IG)*1 Always Below 1 Ω
      J46-3 (IG41) - R23-1 (IG)*2 Always Below 1 Ω
      J46-3 (IG41) - X2-5 (BLB)*9 Always Below 1 Ω
      J46-3 (IG41) - W2-5 (BRB)*9 Always Below 1 Ω
      J46-3 (IG41) - A70-8 (IGB)*10 Always Below 1 Ω
      J46-3 (IG41) - A72-7 (B)*10 Always Below 1 Ω
      J46-3 (IG41) - J75-11 (IG1) Always Below 1 Ω
      J46-3 (IG41) - U14-7 (IGB)*10 Always Below 1 Ω
      J46-3 (IG41) - J73-6 (IG)*11 Always Below 1 Ω
      J46-3 (IG41) - J38-1 (IG)*12 Always Below 1 Ω
      J46-3 (IG41) - K1-2 (IG)*13 Always Below 1 Ω
      J46-2 (B41) - Body ground Always 10 kΩ or higher
      J46-12 (B42) - Body ground Always 10 kΩ or higher
      J46-11 (B43) - Body ground Always 10 kΩ or higher
      J46-3 (IG41) - Body ground Always 10 kΩ or higher
      2C-7 - Body ground Always 10 kΩ or higher

      • *1: for Tire Pressure Warning ECU and Receiver (Stand Alone)

      • *2: for Tire Pressure Warning ECU and Receiver Integrated with Electrical Key Receiver

      • *3: w/ Door Ambient Illumination Light

      • *4: w/ Instrument Panel Ambient Illumination Light

      • *5: w/ Navigation System or Audio and Visual System (for 12.3 Inch Display)

      • *6: w/ Audio and Visual System (for 8 Inch Display)

      • *7: for 8 Inch Display

      • *8: for 12.3 Inch Display

      • *9: w/ Blind Spot Monitor System

      • *10: w/ Lexus Safety System +

      • *11: w/ Panoramic View Monitor System

      • *12: w/ Lexus Parking Assist-sensor System

      • *13: w/ Headup Display System

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR