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DTC B1793: Occupant Classification Sensor Power Supply Circuit Malfunction (03/2012 - 07/2012): Procedure

  1. CHECK CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) 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 sensor 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 (-) battery terminal.
      GTY260461Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    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
      Z1-5 (SVC3) - Body ground Engine switch on (IG) Below 1 V
      Z1-6 (SVC4) - Body ground Engine switch on (IG) Below 1 V
      Z1-11 (SVC1) - Body ground Engine switch on (IG) Below 1 V
      Z1-12 (SVC2) - Body ground Engine 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 engine switch off.
      GTY278950Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Z1-5 (SVC3) - Body ground Always 1 MΩ or higher
      Z1-6 (SVC4) - Body ground Always 1 MΩ or higher
      Z1-11 (SVC1) - Body ground Always 1 MΩ or higher
      Z1-12 (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.
      GTY272222Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      Z1-5 (SVC3) - Z15-1 (SVC3) Always Below 1 Ω
      Z1-6 (SVC4) - Z13-1 (SVC4) Always Below 1 Ω
      Z1-11 (SVC1) - Z14-1 (SVC1) Always Below 1 Ω
      Z1-12 (SVC2) - Z12-1 (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.
      GTY287427Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      Z1-5 (SVC3) - Z1-6 (SVC4) Always 1 MΩ or higher
      Z1-5 (SVC3) - Z1-11 (SVC1) Always 1 MΩ or higher
      Z1-5 (SVC3) - Z1-12 (SVC2) Always 1 MΩ or higher
      Z1-6 (SVC4) - Z1-11 (SVC1) Always 1 MΩ or higher
      Z1-6 (SVC4) - Z1-12 (SVC2) Always 1 MΩ or higher
      Z1-11 (SVC1) - Z1-12 (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 (-) battery terminal.
    3. Turn the engine switch on (IG).
    4. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [03/2012 - ] .
    5. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR [03/2012 - ] .
    6. Turn the engine switch off.
    7. Turn the engine switch on (IG).
    8. Check for DTCs. Refer to DTC CHECK / CLEAR [03/2012 - ] .

      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 engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Replace the occupant classification ECU. Refer to REMOVAL [03/2012 - ] .

      HINT: 

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

    NEXT: Go to next step 

  8. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) battery terminal.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Using the Techstream, perform Zero Point Calibration. Refer to INITIALIZATION [03/2012 - ] .

      OK

      "Zero Point Calibration is complete." is displayed.

    NG → See step   11 

    OK: Go to next step 

  9. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform Sensitivity Check. Refer to INITIALIZATION [03/2012 - ] .

      Standard

      27 to 33 kg (59.5 to 72.8 lb)

    NG → See step   11 

    OK: Go to next step 

  10. CHECK DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR [03/2012 - ] .
    3. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR [03/2012 - ] .
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check for DTCs. Refer to DTC CHECK / CLEAR [03/2012 - ] .

      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 → END 

  11. REPLACE FRONT SEAT ASSEMBLY RH*1 OR FRONT SEAT FRAME WITH ADJUSTER ASSEMBLY RH*2 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
    3. Replace the front seat assembly RH*1 or front seat frame with adjuster assembly RH*2. Refer to REMOVAL [03/2012 - 07/2012] .

      *1: for TMMC Made

      *2: for TMC Made

    NEXT: Go to next step 

  12. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) battery terminal.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Using the Techstream, perform Zero Point Calibration. Refer to INITIALIZATION [03/2012 - ] .

      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 [03/2012 - ] .

      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 [03/2012 - 07/2012] 
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