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Home >> Lexus >> 2010 >> IS 250C Standard >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System (Diagnostic Codes & Circuit Tests) >> Occupant Classification System >> DTC B1774: Pressure Sensor Circuit Malfunction; DTC B1775: Pressure Sensor Power Source Circuit Malfunction >> Procedure
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DTC B1774: Pressure Sensor Circuit Malfunction; DTC B1775: Pressure Sensor Power Source Circuit Malfunction: Procedure

  1. CHECK CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Check that the connectors are properly connected to the occupant classification ECU and occupant classification sensor.

      OK

      The connectors are properly connected.

      HINT: 

      If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

    4. Disconnect the connectors from the occupant classification ECU and occupant classification sensor.
    5. Check that the terminals of the connectors are not damaged.

      OK

      The terminals are not deformed or damaged.

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  2. CHECK FRONT SEAT WIRE RH (SHORT TO B+) 
    1. Connect the cable to the negative (-) battery terminal.
      Fig 1: Inspecting Front Seat Wire RH (Short To B+)
      GTY260177Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Occupant Classification Sensor
      *2 Occupant Classification ECU
      *3 Front Seat Wire RH
      *4 Front view of wire harness connector
      (to Occupant Classification ECU)
      *5 Connector B
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      T16-6 (PS) - Body ground Engine switch on (IG) Below 1 V
      T16-7 (VPS) - Body ground Engine switch on (IG) Below 1 V
      T16-15 (GPS) - Body ground Engine switch on (IG) Below 1 V

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  3. CHECK FRONT SEAT WIRE RH (OPEN) 
    1. Turn the engine switch off.
      Fig 2: Inspecting Front Seat Wire RH (Open)
      GTY278822Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Occupant Classification Sensor *2 Occupant Classification ECU
      *3 Front Seat Wire RH *4 Front view of wire harness connector
      (to Occupant Classification ECU)
      *5 Front view of wire harness connector
      (to Occupant Classification Sensor)      		 *6 Connector B
      *7 Connector C - -
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Using SST, connect terminals 1 (GPS) and 3 (VPS), and connect terminals 2 (PS) and 3 (VPS) of connector C.
      NOTE:

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

      • SST: 09843-18040 
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      T16-6 (PS) - T16-7 (VPS) Always Below 1 Ω
      T16-7 (VPS) - T16-15 (GPS) Always Below 1 Ω

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  4. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND) 
    1. Disconnect SST from connector C.
      Fig 3: Inspecting Front Seat Wire RH (Short To Ground)
      GTY260177Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Occupant Classification Sensor
      *2 Occupant Classification ECU
      *3 Front Seat Wire RH
      *4 Front view of wire harness connector
      (to Occupant Classification ECU)
      *5 Connector B
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      T16-6 (PS) - Body ground Always 1 MΩ or higher
      T16-7 (VPS) - Body ground Always 1 MΩ or higher
      T16-15 (GPS) - Body ground Always 1 MΩ or higher

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  5. CHECK FRONT SEAT WIRE RH (SHORT) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 4: Inspecting Front Seat Wire RH (Short)
      GTY260177Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Occupant Classification Sensor
      *2 Occupant Classification ECU
      *3 Front Seat Wire RH
      *4 Front view of wire harness connector
      (to Occupant Classification ECU)
      *5 Connector B

      Standard Resistance

      Tester Connection Condition Specified Condition
      T16-6 (PS) - T16-15 (GPS) Always 1 MΩ or higher
      T16-7 (VPS) - T16-15 (GPS) Always 1 MΩ or higher

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  6. CHECK DTC 
    1. Connect the connectors to the occupant classification ECU and occupant classification sensor.
    2. Connect the cable to the negative (-) battery terminal.
    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 for 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.

    NG → See step   7 

    OK → See step   11 

  7. INSPECT OCCUPANT CLASSIFICATION SENSOR (FRONT SEAT CUSHION ASSEMBLY) 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Replace the front seat cushion assembly (with occupant classification ECU and occupant classification sensor) with a known good part. Refer to REMOVAL .

      HINT: 

      Perform an inspection using known good parts from another vehicle if possible.

    4. Connect the cable to the negative (-) battery terminal.
    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 

  8. PERFORM ZERO POINT CALIBRATION 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using the Techstream, perform 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, history DTC will remain.

    NEXT: Go to next step 

  9. CHECK DTC 

    HINT: 

    Check that zero point calibration is completed normally. If any of the following conditions are met, DTC B1797 will be output (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 for DTCs. Refer to DTC CHECK / CLEAR .

      OK

      DTC B1797 is not output.

    NG → See step   12 

    OK: Go to next step 

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

    NEXT → END 

  11. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  12. GO TO DTC B1797. Refer to  DTC B1797: Calibration Malfunction  
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