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DTC B1794: Open in Occupant Classification ECU Battery Positive Line [10/2014 - ]: Procedure

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

      Refer to DTC CHECK / CLEAR [10/2014 - ]

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

      Refer to DTC CHECK / CLEAR [10/2014 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Proceed to
      DTC B1794 is not output
      DTC B1794 is output

      HINT: 

      DTCs other than DTC B1794 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1794 is not output 

    USE SIMULATION METHOD TO CHECK. Refer to  DIAGNOSIS SYSTEM [10/2014 - ] 

    Result: 

    DTC B1794 is output 

    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 connector is properly connected to occupant detection ECU.

      Result

      Proceed to
      Connector is properly connected
      Connector is not properly connected

    Result: 

    Connector is not properly connected 

    CONNECT CONNECTOR 

    Result: 

    Connector is properly connected 

    See step  3

  3. CHECK CONNECTOR 
    1. Disconnect the connector from the occupant detection ECU.
    2. Check that the connector (on the occupant detection ECU side) are not damaged.

      Result

      Proceed to
      Connectors are not deformed or damaged
      Connectors are deformed or damaged

    Result: 

    Connectors are deformed or damaged 

    REPLACE HARNESS OR CONNECTOR 

    Result: 

    Connectors are not deformed or damaged 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (OCCUPANT DETECTION ECU - BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY509893Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Occupant Detection ECU)
    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
      f15-1 (+B) - Body ground Always 11 to 14 V
      f15-6 (IG2) - Body ground Engine switch on (IG)
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) 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
      f15-3 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK DTC 
    1. Connect the connector to the occupant detection ECU.
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the engine switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [10/2014 - ]

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

      Refer to DTC CHECK / CLEAR [10/2014 - ]

      Body Electrical > Occupant Detection > Trouble Codes 

      Result

      Proceed to
      DTC B1794 is not output
      DTC B1794 is output

      HINT: 

      DTCs other than DTC B1794 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1794 is not output 

    USE SIMULATION METHOD TO CHECK. Refer to  DIAGNOSIS SYSTEM [10/2014 - ] 

    Result: 

    DTC B1794 is output 

    See step  6

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

      Refer to REMOVAL [10/2014 - 05/2019] , or refer to REMOVAL [05/2019 - ]

      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 (-) battery terminal, and wait for at least 2 seconds.
    2. Turn the engine switch on (IG).
    3. Perform the zero point calibration.

      Refer to INITIALIZATION [10/2014 - ]

      Result

      Proceed to
      "Zero Point Calibration is complete." is displayed

    Result: 

    "Zero Point Calibration is complete." is displayed 

    See step  8

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

      Refer to INITIALIZATION [10/2014 - ]

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE) 

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