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Home >> Toyota >> 2021 >> Land Cruiser Base >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System - Diagnostic Codes & Symptom Tests >> Occupant Classification System >> DTC B1774: Pressure Sensor Circuit Malfunction; DTC B1775: Pressure Sensor Power Source Circuit Malfunction [08/2015 - ] >> Procedure
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DTC B1774: Pressure Sensor Circuit Malfunction; DTC B1775: Pressure Sensor Power Source Circuit Malfunction [08/2015 - ]: Procedure

  1. CHECK FOR DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - ] ).
    3. Clear the DTCs stored in the center airbag sensor (Refer to DTC CHECK / CLEAR [08/2015 - ] ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - ] ).

      OK

      DTC B1774 and B1775 are not output.

      HINT: 

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

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [08/2015 - ] )

    Result: 

    NG 

    See step  2

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

      OK

      Connectors are properly connected.

    Result: 

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    OK 

    See step  3

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

      OK

      Connectors are not deformed or damaged.

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result: 

    OK 

    See step  4

  4. CHECK FRONT SEAT WIRE RH (OCCUPANT DETECTION SENSOR - OCCUPANT CLASSIFICATION ECU) 
    GTY593701Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    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
      c8-6 (PS) - Body ground Engine switch on (IG) Below 1 V
      c8-7 (VPS) - Body ground
      c8-15 (GPS) - Body ground
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Using 2 service wires, 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 a service wire.

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      c8-6 (PS) - c8-7 (VPS) Always Below 1 Ω
      c8-7 (VPS) - c8-15 (GPS)
    8. Disconnect the service wires from connector C.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      c8-6 (PS) - Body ground Always 1 MΩ or higher
      c8-7 (VPS) - Body ground
      c8-15 (GPS) - Body ground
      c8-6 (PS) - c8-15 (GPS)
      c8-7 (VPS) - c8-15 (GPS)

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result: 

    OK 

    See step  5

  5. CHECK FOR DTC 
    1. Connect the connectors to the occupant classification ECU and the occupant detection 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 [08/2015 - ] ).
    5. Clear the DTCs stored in the center airbag sensor (Refer to DTC CHECK / CLEAR [08/2015 - ] ).
    6. Turn the engine switch off.
    7. Turn the engine switch on (IG).
    8. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - ] ).

      OK

      DTC B1774 and B1775 are not output.

      HINT: 

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

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [08/2015 - ] )

    Result: 

    NG 

    See step  6

  6. REPLACE NO. 1 SEAT CUSHION ASSEMBLY (OCCUPANT CLASSIFICATION ECU AND OCCUPANT DETECTION SENSOR) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using the Techstream, save the ECU data from the ECU which is installed in the vehicle (Refer to REGISTRATION [08/2015 - ] ).
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Replace the No. 1 seat cushion (occupant classification ECU and occupant detection sensor) (Refer to REMOVAL [08/2015 - ] ).
    7. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    8. Turn the engine switch on (IG).
    9. Using the Techstream, load the previous ECU data stored in the Techstream into the new ECU (Refer to REGISTRATION [08/2015 - ] ).
    10. Turn the engine switch off.
    11. Turn the engine switch on (IG).
    12. Clear the DTCs stored in the memory (Refer to DTC CHECK / CLEAR [08/2015 - ] ).

      HINT: 

      If the DTCs are not cleared at this time, past DTCs will remain.

    Result: 

    NEXT 

    See step  7

  7. 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 [08/2015 - ] ).
    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 [08/2015 - ] ).

      HINT: 

      If DTCs are not cleared at this time, past DTCs will remain.

    Result: 

    NEXT 

    See step  8

  8. CHECK FOR DTC 

    HINT: 

    Check that the zero point calibration is completed normally. If one of the following conditions is met, DTC B1797 will be output (refer to Initialization (Refer to INITIALIZATION [08/2015 - ] )):

    • 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 [08/2015 - ] ).
    3. Clear the DTCs stored in the center airbag sensor (Refer to DTC CHECK / CLEAR [08/2015 - ] ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check for DTCs (Refer to DTC CHECK / CLEAR [08/2015 - ] ).

      OK

      DTC B1797 is not output.

      HINT: 

      Codes other than DTC B1797 may be output at this time, but they are not related to this check.

    Result: 

    NG 

    Go to DTC B1797 

    (Refer to DTC B1797: Calibration Malfunction [08/2015 - ] )

    Result: 

    OK 

    See step  9

  9. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check (Refer to INITIALIZATION [08/2015 - ] ).

    Result: 

    NEXT 

    END 

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