LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2012 >> RAV4 EV >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System (Diagnostic Codes & Symptom Tests) >> Occupant Classification System >> DTC B1781: Front Occupant Classification Sensor RH Circuit Malfunction >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC B1781: Front Occupant Classification Sensor RH Circuit Malfunction: Procedure

  1. CHECK FOR DTC 
    1. Turn the ignition switch to ON.
    2. Clear the DTCs.Refer to DTC CHECK / CLEAR .

      HINT: 

      First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.

    3. Turn the ignition switch off.
    4. Turn the ignition switch to ON.
    5. Check the DTCs.Refer to DTC CHECK / CLEAR .

      OK

      DTC B1781 is not output.

      HINT: 

      DTCs other than DTC B1781 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 CONNECTOR 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Check that the connectors are properly connected to the occupant classification ECU and the front occupant classification sensor RH.

      OK

      The connectors are properly connected.

    NG → CONNECT CONNECTOR 

    OK: Go to next step 

  3. CHECK FRONT SEAT WIRE RH (TO B+) 
    1. Disconnect the connectors from the occupant classification ECU and the front occupant classification sensor RH.
      Fig 1: Checking Front Seat Wire RH (To B+)
      GTY242943Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the ignition switch to ON.
    4. Measure the voltage of the wire harness side connector.

      Standard voltage 

      Tester Connection Specified Condition
      a1-2 (SGD2) - Body ground Below 1 V
      a1-8 (SIG2) - Body ground Below 1 V
      a1-12 (SVC2) - Body ground Below 1 V

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  4. CHECK FRONT SEAT WIRE RH (FOR OPEN) 
    1. Turn the ignition switch off.
      Fig 2: Checking Front Seat Wire RH (For Open)
      GTY247915Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Using a service wire, connect terminals a4-1 (SVC2) and a4-3 (SGD2), and connect terminals a4-2 (SIG2) and a4-3 (SGD2) of connector C.
      NOTE:

      Do not forcibly insert a service wire into the terminals of the connector when connecting them.

    4. Measure the resistance of the wire harness side connector.

      Standard resistance 

      Tester Connection Specified Condition
      a1-8 (SIG2) - a1-2 (SGD2) Below 1 Ω
      a1-12 (SVC2) - a1-2 (SGD2) Below 1 Ω

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  5. CHECK FRONT SEAT WIRE RH (FOR SHORT) 
    1. Disconnect the service wire from connector C.
      Fig 3: Checking Front Seat Wire RH (For Short)
      GTY308580Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance of the wire harness side connector.

      Standard resistance 

      Tester Connection Specified Condition
      a1-8 (SIG2) - a1-2 (SGD2) 1 MΩ or higher
      a1-12 (SVC2) - a1-2 (SGD2) 1 MΩ or higher
      a1-8 (SIG2) - a1-12 (SVC2) 1 MΩ or higher

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  6. CHECK FRONT SEAT WIRE RH (TO GROUND) 
    1. Measure the resistance of the wire harness side connector.
      Fig 4: Checking Front Seat Wire RH (For Ground)
      GTY308580Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance 

      Tester Connection Specified Condition
      a1-2 (SGD2) - Body ground 1 MΩ or higher
      a1-8 (SIG2) - Body ground 1 MΩ or higher
      a1-12 (SVC2) - Body ground 1 MΩ or higher

    NG → REPAIR OR REPLACE FRONT SEAT WIRE RH 

    OK: Go to next step 

  7. CHECK FOR DTC 
    1. Connect the connectors to the occupant classification ECU and the front occupant classification sensor RH.
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the ignition switch to ON.
    4. Clear the DTCs.Refer to DTC CHECK / CLEAR .

      HINT: 

      First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor.

    5. Turn the ignition switch off.
    6. Turn the ignition switch to ON.
    7. Check the DTCs.Refer to DTC CHECK / CLEAR .

      OK

      DTC B1781 is not output.

      HINT: 

      DTCs other than DTC B1781 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 cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the occupant classification ECU.Refer to COMPONENTS .

      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 cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch to ON.
    4. Using the Techstream, perform the zero point calibration.Refer to INITIALIZATION .

      OK

      "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 the 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 FOR DTC 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    2. Turn the ignition switch to ON.
    3. Clear the DTCs.Refer to DTC CHECK / CLEAR .

      HINT: 

      First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.

    4. Turn the ignition switch off.
    5. Turn the ignition switch to ON.
    6. Check the DTCs.Refer to DTC CHECK / CLEAR .

      OK

      DTC B1781 is not output.

      HINT: 

      DTCs other than DTC B1781 may be output at this time, but they are not related to this check.

    OK → END 

    NG: Go to next step 

  12. REPLACE FRONT SEAT WITH ADJUSTER FRAME ASSEMBLY RH 
    1. Turn the ignition switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the front seat with adjuster frame assembly RH.Refer to COMPONENTS .

    NEXT: Go to next step 

  13. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch to ON.
    4. Using the Techstream, perform the zero point calibration.Refer to INITIALIZATION .

      OK

      "Zero Point Calibration is complete." is displayed.

    NEXT: Go to next step 

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

      Standard value 

      27 to 33 kg (59.52 to 72.75 lb)

    NEXT → END 

scientia non olet · About LEMON Manuals