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Home >> Lexus >> 2009 >> ES 350 >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System (Diagnostic Codes) >> Occupant Classification System >> DTC B1774: Pressure Sensor Circuit Malfunction; DTC B1775: Pressure Sensor Power Source Circuit Malfunction >> Procedure

DTC B1774: Pressure Sensor Circuit Malfunction; DTC B1775: Pressure Sensor Power Source Circuit Malfunction: Procedure

  1. CHECK DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
    3. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR .
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check the DTCs . Refer to DTC CHECK / CLEAR .

      OK

      DTC B1774 and B1775 are not output.

      HINT: 

      Codes other than B1774 and B1775 may be output at this time, but they are not related to this check.

    OK → See step   13 

    NG: Go to next step 

  2. CHECK CONNECTION OF CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
    3. Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensor.

      OK

      The connectors are properly connected.

    NG → CONNECT CONNECTORS PROPERLY, THEN GO TO STEP 1 

    OK: Go to next step 

  3. CHECK CONNECTORS 
    1. Disconnect the connectors from the occupant classification ECU and the occupant classification sensor.
    2. Check that the connectors (on the occupant classification ECU side and occupant classification sensor side) are not damaged.

      OK

      The connectors are not deformed or damaged.

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  4. CHECK FRONT SEAT WIRE RH (SHORT TO B+) 
    1. Connect the negative (-) terminal cable to the battery.
      Fig 1: Identifying Front Seat Wire RH (Short To B+)
      GTY135331Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Condition Specified Condition
      T4-6 (PS) - Body ground Engine switch on (IG) Below 1 V
      T4-7 (VPS) - Body ground Engine switch on (IG) Below 1 V
      T4-15 (GPS) - Body ground Engine switch on (IG) Below 1 V

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  5. CHECK FRONT SEAT WIRE RH (OPEN) 
    1. Turn the engine switch off.
      Fig 2: Checking Front Seat Wire RH (Open)
      GTY133679Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
    3. Using a service wire, connect terminals 1 (GPS) and 3 (VPS), and connect terminals 2 (PS) and 3 (VPS) of connector C.
      NOTE:

      Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

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

      Standard resistance

      Tester Connection Condition Specified Condition
      T4-6 (PS) - T4-7 (VPS) Always Below 1 Ω
      T4-7 (VPS) - T4-15 (GPS) Always Below 1 Ω

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  6. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND) 
    1. Disconnect the service wire from connector C.
      Fig 3: Identifying Front Seat Wire RH (Short To Ground)
      GTY135331Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      T4-6 (PS) - Body ground Always 1 MΩ or higher
      T4-7 (VPS) - Body ground Always 1 MΩ or higher
      T4-15 (GPS) - Body ground Always 1 MΩ or higher

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  7. CHECK FRONT SEAT WIRE RH (SHORT) 
    Fig 4: Identifying Front Seat Wire RH (Short)
    GTY135331Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      T4-6 (PS) - T4-15 (GPS) Always 1 MΩ or higher
      T4-7 (VPS) - T4-15 (GPS) Always 1 MΩ or higher

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  8. CHECK DTC 
    1. Connect the connectors to the occupant classification ECU and the occupant classification sensor.
    2. Connect the negative (-) terminal cable to the battery.
    3. Turn the engine switch on (IG).
    4. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
    5. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR .
    6. Turn the engine switch off.
    7. Turn the engine switch on (IG).
    8. Check the DTCs . Refer to DTC CHECK / CLEAR .

      OK

      DTCs B1774 and B1775 are not output.

      HINT: 

      Codes other than B1774 and B1775 may be output at this time, but they are not related to this check.

    OK → See step   13 

    NG: Go to next step 

  9. REPLACE OCCUPANT CLASSIFICATION SENSOR (FRONT SEAT CUSHION ASSEMBLY) 
    1. Turn the engine switch off.
    2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
    3. Replace the front seat cushion assembly (with occupant classification ECU and occupant classification sensor) . Refer to REMOVAL .

      HINT: 

      Perform the inspection using parts from a normal vehicle if possible.

    4. Connect the negative (-) terminal cable to the battery.
    5. Turn the engine switch on (IG).
    6. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
    7. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR .
    8. Turn the engine switch off.
    9. Turn the engine switch on (IG).
    10. Check the DTCs . Refer to DTC CHECK / CLEAR .

      OK

      DTC B1774 and B1775 are not output.

      HINT: 

      Codes other than B1774 and B1775 may be output at this time, but they are not related to this check.

    NEXT: Go to next step 

  10. PERFORM ZERO POINT CALIBRATION 
    1. Connect Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using Techstream, perform the zero point calibration . Refer to INITIALIZATION .
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Clear the DTCs stored in the memory . Refer to DTC CHECK / CLEAR .

      HINT: 

      If DTC is not cleared at this time, past DTC will remain.

    NEXT: Go to next step 

  11. CHECK DTC 

    HINT: 

    Check that the zero point calibration is completed normally. If any of the following conditions is met, DTC B1797 will be output (Refer to INITIALIZATION: . Refer to INITIALIZATION ):

    • Zero point calibration is performed when the conditions for the calibration are not satisfied.
    • Zero point calibration has failed.
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU . Refer to DTC CHECK / CLEAR .
    3. Clear the DTCs stored in the center airbag sensor assembly . Refer to DTC CHECK / CLEAR .
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check the DTCs . Refer to DTC CHECK / CLEAR .

      OK

      DTC B1797 is not output.

    NG → See step   14 

    OK: Go to next step 

  12. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check . Refer to INITIALIZATION .

    NEXT → END 

  13. USE SIMULATION METHOD TO CHECK. Refer to  DIAGNOSIS SYSTEM 
  14. GO TO DTC B1797. Refer to  DTC B1797: Calibration Malfunction  
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