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DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction [08/2014 - ]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Check that the connectors are properly connected to the 4 occupant classification sensors and occupant classification ECU.

      OK

      The connectors are properly connected.

      HINT: 

      If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

    4. Disconnect the connectors from the 4 occupant classification sensors and occupant classification ECU.
    5. Check that the terminals of connectors are not damaged.

      OK

      The terminals are not deformed or damaged.

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  2. CHECK FRONT SEAT WIRE RH (SHORT TO B+) 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      GTY227250Courtesy 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 Condition Specified Condition
      W2-5 (SVC3) - Body ground Power switch on (IG) Below 1 V
      W2-6 (SVC4) - Body ground Power switch on (IG) Below 1 V
      W2-11 (SVC1) - Body ground Power switch on (IG) Below 1 V
      W2-12 (SVC2) - Body ground Power switch on (IG) Below 1 V
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Occupant Classification ECU)

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  3. CHECK FRONT SEAT WIRE RH (SHORT TO GROUND) 
    1. Turn the power switch off.
      GTY227250Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      W2-5 (SVC3) - Body ground Always 1 MΩ or higher
      W2-6 (SVC4) - Body ground Always 1 MΩ or higher
      W2-11 (SVC1) - Body ground Always 1 MΩ or higher
      W2-12 (SVC2) - Body ground Always 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Occupant Classification ECU)

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  4. CHECK FRONT SEAT WIRE RH (OPEN) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY230436Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      W2-5 (SVC3) - W1-1 (SVC3) Always Below 1 Ω
      W2-6 (SVC4) - W7-1 (SVC4) Always Below 1 Ω
      W2-11 (SVC1) - W4-1 (SVC1) Always Below 1 Ω
      W2-12 (SVC2) - W6-1 (SVC2) Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Occupant Classification Sensor)
      *2 Front LH
      *3 Front RH
      *4 Rear LH
      *5 Rear RH
      *6 Front view of wire harness connector
      (to Occupant Classification ECU)

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  5. CHECK FRONT SEAT WIRE RH (SHORT) 
    1. Measure the resistance according to the value(s) in the table below.
      GTY227250Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      W2-5 (SVC3) - W2-6 (SVC4) Always 1 MΩ or higher
      W2-5 (SVC3) - W2-11 (SVC1) Always 1 MΩ or higher
      W2-5 (SVC3) - W2-12 (SVC2) Always 1 MΩ or higher
      W2-6 (SVC4) - W2-11 (SVC1) Always 1 MΩ or higher
      W2-6 (SVC4) - W2-12 (SVC2) Always 1 MΩ or higher
      W2-11 (SVC1) - W2-12 (SVC2) Always 1 MΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Occupant Classification ECU)

    NG → REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  6. CHECK DTC 
    1. Connect the connectors to the occupant classification ECU and 4 occupant classification sensors.
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the power switch on (IG).
    4. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [08/2014 - ] .
    5. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR [08/2014 - ] .
    6. Turn the power switch off.
    7. Turn the power switch on (IG).
    8. Check for DTCs. Refer to DTC CHECK / CLEAR [08/2014 - ] .

      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.

    NG → See step   7 

    OK → See step   14 

  7. REPLACE OCCUPANT CLASSIFICATION ECU 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Replace the occupant classification ECU. Refer to REMOVAL [08/2014 - ] .

      HINT: 

      Perform the following inspection using known good parts from another vehicle if possible.

    NEXT: Go to next step 

  8. CHECK DTC 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
    2. Turn the power switch on (IG).
    3. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [08/2014 - ] .
    4. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR [08/2014 - ] .
    5. Turn the power switch off.
    6. Turn the power switch on (IG).
    7. Check for DTCs. Refer to DTC CHECK / CLEAR [08/2014 - ] .

      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.

    NG → See step   11 

    OK: Go to next step 

  9. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
    2. Connect the Techstream to the DLC3.
    3. Turn the power switch on (IG).
    4. Using the Techstream, perform Zero Point Calibration. Refer to INITIALIZATION [08/2014 - ] .

      OK

      "Zero Point Calibration is complete." is displayed.

    NEXT: Go to next step 

  10. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform Sensitivity Check. Refer to INITIALIZATION [08/2014 - ] .

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

    NEXT → END 

  11. REPLACE FRONT SEAT CUSHION SPRING ASSEMBLY RH 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Replace the front seat cushion spring assembly RH. Refer to DISASSEMBLY [08/2014 - ] .

    NEXT: Go to next step 

  12. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
    2. Connect the Techstream to the DLC3.
    3. Turn the power switch on (IG).
    4. Using the Techstream, perform Zero Point Calibration. Refer to INITIALIZATION [08/2014 - ] .

      OK

      "Zero Point Calibration is complete." is displayed.

    NEXT: Go to next step 

  13. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform Sensitivity Check. Refer to INITIALIZATION [08/2014 - ] .

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

    NEXT → END 

  14. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [08/2014 - ] 
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