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DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction [06/2015 - ]: Procedure

  1. CHECK DTC 
    1. Turn the power switch on (IG), and wait for at least 60 seconds.
    2. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [06/2015 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

      HINT: 

      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.
      • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.
    3. Turn the power switch off.
    4. Turn the power switch on (IG), and wait for at least 60 seconds.
    5. Check for DTCs.

      Refer to DTC CHECK / CLEAR [06/2015 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Result Proceed to
      DTC B1793 is not output A
      DTC B1793 is output B

      HINT: 

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

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  DIAGNOSIS SYSTEM [06/2015 - ] 

    Result: 

    B 

    See step  2

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

      Result

      Result Proceed to
      Connectors are properly connected A
      Connectors are not properly connected B

    Result: 

    B 

    CHECK CONNECTORS 

    Result: 

    A 

    See step  3

  3. CHECK CONNECTORS 
    1. Disconnect the connectors from the occupant detection ECU, front and rear occupant classification sensor LH.
      GTY497026Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Occupant Classification Sensor LH
      *2 Rear Occupant Classification Sensor LH
      *3 Occupant Detection ECU
      *4 Front Seat Wire RH
    2. Check that the connectors (on the occupant detection ECU side, front and rear occupant classification sensor LH side) are not damaged.

      Result

      Result Proceed to
      Connectors are not deformed or damaged A
      Connectors are deformed or damaged B

    Result: 

    B 

    REPLACE FRONT SEAT WIRE RH 

    Result: 

    A 

    See step  4

  4. CHECK FRONT SEAT WIRE RH 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
      GTY599010Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Wire RH *2 Front Occupant Classification Sensor LH
      *3 Rear Occupant Classification Sensor LH *4 Occupant Detection ECU
      *5 Connector B *6 Connector C
      *7 Connector E - -
      *a Front view of wire harness connector
      (to Occupant Detection ECU)      		 *b Front view of wire harness connector
      (to Front Occupant Classification Sensor LH)
      *c Front view of wire harness connector
      (to Rear Occupant Classification Sensor LH)      		 - -
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      Z12-1 (SVC1) - Body ground Power switch on (IG) Below 1 V
      Z12-2 (SVC3) - Body ground
    4. Turn the power switch off.
    5. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Z12-1 (SVC1) - Z15-1 (SVC) Always Below 1 Ω
      Z12-2 (SVC3) - Z16-1 (SVC)
      Z12-1 (SVC1) - Z12-2 (SVC3) 1 MΩ or higher
      Z12-1 (SVC1) - Body ground
      Z12-2 (SVC3) - Body ground

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT WIRE RH 

    Result: 

    OK 

    See step  5

  5. CHECK DTC 
    1. Connect the connectors to the occupant detection ECU, front and rear occupant classification sensor LH.
    2. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    3. Turn the power switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [06/2015 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

      HINT: 

      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.
      • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.
    5. Turn the power switch off.
    6. Turn the power switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs.

      Refer to DTC CHECK / CLEAR [06/2015 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Result Proceed to
      DTC B1793 is not output A
      DTC B1793 is output B

      HINT: 

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

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  DIAGNOSIS SYSTEM [06/2015 - ] 

    Result: 

    B 

    See step  6

  6. REPLACE OCCUPANT DETECTION ECU 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
    3. Replace the occupant detection ECU.

      Refer to REMOVAL [06/2015 - 11/2018] , or refer to REMOVAL [11/2018 - ]

      HINT: 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  7

  7. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    2. Turn the power switch on (IG).
    3. Perform the zero point calibration.

      Refer to INITIALIZATION [06/2015 - ]

      Result

      Result Proceed to
      "Zero Point Calibration is complete." is displayed A
      "Zero Point Calibration is complete." is not displayed B

    Result: 

    B 

    See step  10

    Result: 

    A 

    See step  8

  8. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check.

      Refer to INITIALIZATION [06/2015 - ]

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  9

  9. CHECK DTC 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [06/2015 - ]

      Body Electrical > Occupant Detection > Clear DTCs 

      HINT: 

      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the airbag sensor assembly.
      • Use the Techstream to clear the DTCs of the occupant detection ECU, otherwise the DTCs cannot be cleared.
    2. Turn the power switch off.
    3. Turn the power switch on (IG), and wait for at least 60 seconds.
    4. Check for DTCs.

      Refer to DTC CHECK / CLEAR [06/2015 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Result Proceed to
      DTC B1793 is not output A
      DTC B1793 is output B

      HINT: 

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

    Result: 

    A 

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE) 

    Result: 

    B 

    See step  10

  10. REPLACE FRONT SEAT ADJUSTER ASSEMBLY LH (FRONT AND REAR OCCUPANT CLASSIFICATION SENSOR LH) 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
    3. Replace the front seat adjuster assembly RH.

      Refer to DISASSEMBLY [06/2015 - ]

      HINT: 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  11

  11. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    2. Turn the power switch on (IG).
    3. Perform the zero point calibration.

      Refer to INITIALIZATION [06/2015 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  12

  12. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check.

      Refer to INITIALIZATION [06/2015 - ]

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END (FRONT SEAT ADJUSTER ASSEMBLY RH [FRONT AND REAR OCCUPANT CLASSIFICATION SENSOR LH] WAS DEFECTIVE) 

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