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 40 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 40 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 or yaw rate sensor, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.

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  • When the engine stop and start ECU is replaced, check the oil pump assembly with solenoid.

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  • 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 A93 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
      A93-1 (BIN2) - BBC NO. 2 fuse terminal 2 Always Below 1 Ω
      A93-3 (BIN1) - BBC NO. 1 fuse terminal 2 Always Below 1 Ω
      A93-1 (BIN2) - Body ground Always 10 kΩ or higher
      BBC NO. 2 fuse terminal 2 - Body ground Always 10 kΩ or higher
      A93-3 (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. B003X1AC14
      *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
      A93-1 (BIN2) - Body ground Always 9.5 to 14 V
      A93-3 (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
      K139-21 (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 A93 and A94 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
      A93-2 (GND2) - Body ground Always Below 1 Ω
      A93-8 (GND1) - Body ground Always Below 1 Ω
      A94-6 (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 K139 engine stop and start ECU connector.

    2. Disconnect the Q36 tire pressure warning ECU and receiver connector.*1

    3. Disconnect the Q38 tire pressure warning ECU and receiver connector.*2

    4. Disconnect the N6 front door inside handle illumination light assembly RH connector.

    5. Disconnect the N21 front door inside handle illumination light assembly LH connector.

    6. Disconnect the K70 radio receiver assembly connector.*3

    7. Disconnect the K58 radio receiver assembly connector.*4

    8. Disconnect the K61 multi-display assembly connector.*5

    9. Disconnect the K78 remote touch connector.*4

    10. Disconnect the Q50 blind spot monitor sensor LH connector.*6

    11. Disconnect the Q51 blind spot monitor sensor RH connector.*6

    12. Disconnect the S6 inner rear view mirror assembly connector.*7

    13. Disconnect the B10 millimeter wave radar sensor assembly connector.*8

    14. Disconnect the M2 driving support ECU assembly connector.*8

    15. Disconnect the K141 network gateway ECU connector.

    16. Disconnect the S18 forward recognition camera connector.*8

    17. Disconnect the K65 air conditioning control assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K139-2 (B41) - Q36-7 (+B)*1 Always Below 1 Ω
      K139-2 (B41) - Q38-7 (+B)*2 Always Below 1 Ω
      K139-2 (B41) - N6-1 (+) Always Below 1 Ω
      K139-2 (B41) - N21-1 (+) Always Below 1 Ω
      K139-12 (B42) - K70-4 (+B1)*3 Always Below 1 Ω
      K139-12 (B42) - K58-17 (+B1)*4 Always Below 1 Ω
      K139-11 (B43) - K61-12 (B)*5 Always Below 1 Ω
      K139-11 (B43) - K78-1 (+B)*4 Always Below 1 Ω
      K139-3 (IG41) - Q36-1 (IG)*1 Always Below 1 Ω
      K139-3 (IG41) - Q38-1 (IG)*2 Always Below 1 Ω
      K139-3 (IG41) - Q50-5 (BLB)*6 Always Below 1 Ω
      K139-3 (IG41) - Q51-5 (BRB)*6 Always Below 1 Ω
      K139-3 (IG41) - S6-1 (IG)*7 Always Below 1 Ω
      K139-3 (IG41) - B10-8 (IGB)*8 Always Below 1 Ω
      K139-3 (IG41) - M2-7 (B)*8 Always Below 1 Ω
      K139-3 (IG41) - K141-11 (IG1) Always Below 1 Ω
      K139-3 (IG41) - S18-7 (IGB)*8 Always Below 1 Ω
      K139-3 (IG41) - K65-8 (IG+) Always Below 1 Ω
      K139-2 (B41) - Body ground Always 10 kΩ or higher
      K139-12 (B42) - Body ground Always 10 kΩ or higher
      K139-11 (B43) - Body ground Always 10 kΩ or higher
      K139-3 (IG41) - Body ground Always 10 kΩ or higher

      • *1: w/ ECE-R64 Type Tire Pressure Warning System

      • *2: w/ FMVSS138 Type Tire Pressure Warning System

      • *3: for Audio and Visual System (w/o Parallel Parking Assist Function)

      • *4: w/ Navigation System or Audio and Visual System (w/ Parallel Parking Assist Function)

      • *5: w/ Multi-display

      • *6: w/ Blind Spot Monitor System

      • *7: w/ Auto Glare-resistant EC Mirror

      • *8: w/ Lexus Safety System +

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR