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DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction [08/2015 - 08/2019]: Procedure

  1. CHECK FOR DTC 
    1. Turn the ignition switch to ON, and wait for at least 60 seconds.
    2. Clear the DTCs stored in memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
      • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
    3. Turn the ignition switch off.
    4. Turn the ignition switch to ON, and wait for at least 60 seconds.
    5. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      OK

      DTC B1793 is not output.

      HINT: 

      DTCs other than DTC B1793 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 ignition 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 occupant classification sensors.

      OK

      Connectors are properly connected.

    Result: 

    NG 

    CONNECT CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK CONNECTOR 
    1. Disconnect the connectors from the occupant classification ECU and 4 occupant classification sensors.
    2. Check that the connectors (on the occupant classification ECU side and occupant classification sensor side) are not damaged (Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [08/2015 - ] ).

      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 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY705404Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 Front Seat Wire RH *2 Occupant Classification Sensor
      *3 Occupant Classification ECU *4 Connector B
      *5 Connector C - -
      *a Front view of wire harness connector
      (to Occupant Classification ECU)      		 *b Front view of wire harness connector
      (to Front Occupant Classification Sensor LH)
      *c Front view of wire harness connector
      (to Front Occupant Classification Sensor RH)      		 *d Front view of wire harness connector
      (to Rear Occupant Classification Sensor LH)
      *e Front view of wire harness connector
      (to Rear Occupant Classification Sensor RH)      		 - -
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      a10-11 (SVC1) - Body ground Ignition switch ON Below 1 V
      a10-12 (SVC2) - Body ground
      a10-5 (SVC3) - Body ground
      a10-6 (SVC4) - Body ground
    3. Turn the ignition switch off.
    4. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      a10-11 (SVC1) - a8-1 (SVC1) Always Below 1 Ω
      a10-12 (SVC2) - a6-1 (SVC2)
      a10-5 (SVC3) - a11-1 (SVC3)
      a10-6 (SVC4) - a5-1 (SVC4)
      a10-11 (SVC1) - a10-12 (SVC2) Always 1 MΩ or higher
      a10-11 (SVC1) - a10-5 (SVC3)
      a10-11 (SVC1) - a10-6 (SVC4)
      a10-12 (SVC2) - a10-5 (SVC3)
      a10-12 (SVC2) - a10-6 (SVC4)
      a10-5 (SVC3) - a10-6 (SVC4)
      a10-11 (SVC1) - Body ground
      a10-12 (SVC2) - Body ground
      a10-5 (SVC3) - Body ground
      a10-6 (SVC4) - Body ground

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result: 

    OK 

    See step  5

  5. CHECK FOR DTC 
    1. Connect the connectors to occupant classification ECU and 4 occupant classification sensors.
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the ignition switch to ON, and wait for at least 60 seconds.
    4. Clear the DTCs stored in memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
      • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
    5. Turn the ignition switch off.
    6. Turn the ignition switch to ON, and wait for at least 60 seconds.
    7. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      OK

      DTC B1793 is not output.

      HINT: 

      DTCs other than DTC B1793 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 OCCUPANT CLASSIFICATION ECU 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the occupant classification ECU (Refer to REMOVAL [08/2015 - ] ).

      HINT: 

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

    Result: 

    NEXT 

    See step  7

  7. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    2. Turn the ignition switch to ON, and wait for at least 60 seconds.
    3. Using the Techstream, perform the zero point calibration (Refer to INITIALIZATION [08/2015 - ] ).

      OK

      "Zero Point Calibration is complete." is displayed.

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  8

  8. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform the sensitivity check (Refer to INITIALIZATION [08/2015 - ] ).

      Standard range

      27 to 33 kg (59.5 to 72.8 lb)

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  9

  9. CHECK FOR DTC 
    1. Clear the DTCs stored in memory (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      HINT: 

      • First clear the DTCs stored in the occupant classification ECU, and then clear the DTCs stored in the center airbag sensor.
      • Use the Techstream to clear the DTCs of the occupant classification ECU, otherwise the DTCs cannot be cleared.
    2. Turn the ignition switch off.
    3. Turn the ignition switch to ON, and wait for at least 60 seconds.
    4. Using the Techstream, check for DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] ).

      OK

      DTC B1793 is not output.

      HINT: 

      DTCs other than DTC B1793 may be output at this time, but they are not related to this check.

    Result: 

    OK 

    END 

    Result: 

    NG 

    See step  10

  10. REPLACE SEPARATE TYPE FRONT SEAT CUSHION SPRING ASSEMBLY 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. for Manual Seat:
      1. Replace the separate type front seat cushion spring RH (Refer to DISASSEMBLY [08/2015 - ] ).
    4. for Power Seat:
      1. Replace the separate type front seat cushion spring RH (Refer to DISASSEMBLY [08/2015 - ] ).

      HINT: 

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

    Result: 

    NEXT 

    See step  11

  11. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    2. Turn the ignition switch to ON, and wait for at least 60 seconds.
    3. Using the Techstream, perform the zero point calibration (Refer to INITIALIZATION [08/2015 - ] ).

      OK

      "Zero Point Calibration is complete." is displayed.

    Result: 

    NEXT 

    See step  12

  12. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform the sensitivity check (Refer to INITIALIZATION [08/2015 - ] ).

      Standard range

      27 to 33 kg (59.5 to 72.8 lb)

    Result: 

    NEXT 

    END 

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