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DTC B1794: Open in Occupant Classification ECU Battery Positive Line [09/2014 - ]: Procedure

  1. CHECK FOR DTC 
    1. Turn the power switch on (IG), and wait for at least 60 seconds.
    2. Clear the DTCs (Refer to DTC CHECK / CLEAR [09/2014 - ] ).

      HINT: 

      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the center airbag sensor.
      • 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 [09/2014 - ] ).

      OK

      DTC B1794 is not output.

      HINT: 

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

    Result:  OK

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [09/2014 - ] )

    Result:  NG

    NG 

    See step  2

  2. CHECK CONNECTION OF CONNECTOR 
    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 center airbag sensor, rear occupant classification sensor LH and RH and occupant detection ECU.

      OK

      Connectors are properly connected.

    Result:  NG

    NG 

    CONNECT CONNECTOR 

    Result:  OK

    OK 

    See step  3

  3. CHECK CONNECTOR 
    1. Disconnect the connector from the occupant detection ECU.
    2. Check that the connectors (on the occupant detection ECU side) are not damaged (Refer to DIAGNOSIS SYSTEM [09/2014 - ] ).

      OK

      Connectors are not deformed or damaged.

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (SOURCE VOLTAGE AND BODY GROUND) 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
      GTY524153Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    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 (+B) - Body ground Always 11 to 14 V
      z12-6 (IG) - Body ground Power switch on (IG)
    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
      z12-3 (GND) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Occupant Detection ECU)

    Result:  NG

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  5

  5. CHECK FOR DTC 
    1. Connect the connectors to the occupant detection ECU.
    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 [09/2014 - ] ).

      HINT: 

      • First clear the DTCs stored in the occupant detection ECU, and then clear the DTCs stored in the center airbag sensor.
      • 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 [09/2014 - ] ).

      OK

      DTC B1794 is not output.

      HINT: 

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

    Result:  OK

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [09/2014 - ] )

    Result:  NG

    NG 

    See step  6

  6. CHECK 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 DIAGNOSIS SYSTEM [09/2014 - ] ).

      HINT: 

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

    Result:  NEXT

    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 [09/2014 - ] ).

      OK

      "Zero Point Calibration is complete." is displayed.

    Result:  NEXT

    NEXT 

    See step  8

  8. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check (Refer to INITIALIZATION [09/2014 - ] ).

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

    Result:  NEXT

    NEXT 

    END (OCCUPANT DETECTION ECU WAS DEFECTIVE) 

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