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Home >> Toyota >> 2012 >> Avalon Base >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System (Diagnostic Codes & Symptom Tests) >> Occupant Classification System >> DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction >> Procedure
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DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction: Procedure

  1. CHECK DTC 
    1. Turn the ignition switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
    3. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR .
    4. Turn the ignition switch off.
    5. Turn the ignition switch on (IG).
    6. Check the DTCs. Refer to DTC CHECK / CLEAR .

      OK

      DTC B1793 is not output.

      HINT: 

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

    OK → USE SIMULATION METHOD TO CHECK 

    NG: Go to next step 

  2. CHECK CONNECTION OF CONNECTORS 
    1. Turn the ignition switch off.
    2. Disconnect the negative (-) terminal cable from the battery.
    3. Check that the connectors are properly connected to the occupant classification ECU and the occupant classification sensors.

      OK

      The connectors are connected.

    NG → CONNECT CONNECTORS, THEN GO TO STEP   1 

    OK: Go to next step 

  3. CHECK FRONT SEAT WIRE RH (SHORT TO B+) 
    1. Disconnect the connectors from the occupant classification ECU and the 4 occupant classification sensors.
      Fig 1: Checking Front Seat Wire RH (Short To B+)
      GTY167334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect the negative (-) terminal cable to the battery.
    3. Turn the ignition switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester connection Condition Specified condition
      O2-5 (SVC3) - Body ground Ignition switch on (IG) Below 1 V
      O2-6 (SVC4) - Body ground Ignition switch on (IG) Below 1 V
      O2-11 (SVC1) - Body ground Ignition switch on (IG) Below 1 V
      O2-12 (SVC2) - Body ground Ignition switch on (IG) Below 1 V

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  4. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND) 
    1. Turn the ignition switch off.
      Fig 2: Checking Front Seat Wire RH (Short To Ground)
      GTY167334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the negative (-) terminal cable from the battery.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester connection Condition Specified condition
      O2-5 (SVC3) - Body ground Always 1 MΩ or Higher
      O2-6 (SVC4) - Body ground Always 1 MΩ or Higher
      O2-11 (SVC1) - Body ground Always 1 MΩ or Higher
      O2-12 (SVC2) - Body ground Always 1 MΩ or Higher

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  5. CHECK FRONT SEAT WIRE RH (OPEN) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 3: Checking Front Seat Wire RH (Open)
      GTY167334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance

      Tester connection Condition Specified condition
      O2-5 (SVC3) - O6-1 (SVC3) Always Below 1 Ω
      O2-6 (SVC4) - O8- 1 (SVC4) Always Below 1 Ω
      O2-11 (SVC1) - O5-1 (SVC1) Always Below 1 Ω
      O2-12 (SVC2) - O7-1 (SVC2) Always Below 1 Ω

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  6. CHECK FRONT SEAT WIRE RH (SHORT) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 4: Checking Front Seat Wire RH (Short)
      GTY167334Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance

      Tester connection Condition Specified condition
      O2-5 (SVC3) - O2-6 (SVC4) Always 1 MΩ or Higher
      O2-5 (SVC3) - O2-11 (SVC1) Always 1 MΩ or Higher
      O2-5 (SVC3) - O2-12 (SVC2) Always 1 MΩ or Higher
      O2-6 (SVC4) - O2-11 (SVC1) Always 1 MΩ or Higher
      O2-6 (SVC4) - O2-12 (SVC2) Always 1 MΩ or Higher
      O2-11 (SVC1) - O2-12 (SVC2) Always 1 MΩ or Higher

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  7. CHECK DTC 
    1. Connect the connectors to the occupant classification ECU and the 4 occupant classification sensors.
    2. Connect the negative (-) terminal cable to the battery.
    3. Turn the ignition switch on (IG).
    4. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
    5. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR .
    6. Turn the ignition switch off.
    7. Turn the ignition switch on (IG).
    8. Check the DTCs. Refer to DTC CHECK / CLEAR .

      OK

      DTC B1793 is not output.

      HINT: 

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

    OK → USE SIMULATION METHOD TO CHECK 

    NG: Go to next step 

  8. REPLACE OCCUPANT CLASSIFICATION ECU 
    1. Turn the ignition switch off.
    2. Disconnect the negative (-) terminal cable from the battery.
    3. Replace the occupant classification ECU. Refer to REMOVAL .

      HINT: 

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

    NEXT: Go to next step 

  9. PERFORM ZERO POINT CALIBRATION 
    1. Connect the negative (-) terminal cable to the battery.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch on (IG).
    4. Using the Techstream, perform "Zero point calibration". Refer to INITIALIZATION .

      OK

      The "Zero Point Calibration is complete." is displayed.

    NG → See step   12 

    OK: Go to next step 

  10. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform "Sensitivity check". Refer to INITIALIZATION .

      Standard value

      27 to 33 kg (59.52 to 72.75 lb)

    NG → See step   12 

    OK: Go to next step 

  11. CHECK DTC 
    1. Turn the ignition switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
    3. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR .
    4. Turn the ignition switch off.
    5. Turn the ignition switch on (IG).
    6. Check the DTCs. Refer to DTC CHECK / CLEAR .

      OK

      DTC B1793 is not output.

      HINT: 

      Codes other than DTC B1793 may be output at this time, but they are related to this check.

    OK → END 

    NG: Go to next step 

  12. REPLACE FRONT SEAT FRAME WITH ADJUSTER ASSEMBLY RH 
    1. Turn the ignition switch off.
    2. Disconnect the negative (-) terminal cable from the battery.
    3. Replace the front seat frame with adjuster assembly RH. Refer to REMOVAL for power seat or REMOVAL for manual seat.

    NEXT: Go to next step 

  13. PERFORM ZERO POINT CALIBRATION 
    1. Connect the negative (-) terminal cable to the battery.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch on (IG).
    4. Using the Techstream, perform "Zero point calibration". Refer to INITIALIZATION .

      OK

      The "Zero Point Calibration is complete." is displayed.

    NEXT: Go to next step 

  14. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform "Sensitivity check". Refer to INITIALIZATION .

      Standard value

      27 to 33 kg (59.52 to 72.75 lb)

    NEXT → END 

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