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Home >> Lexus >> 2007 >> RX 400h AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 320 (Supplemental Restraint System) >> Occupant Classification System >> DTC B1794 Open in Occupant Classification ECU Battery Positive Line >> Inspection Procedure
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Inspection Procedure

WARNING: This page is about a different car, the 2008 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR DTC 
    1. Turn the ignition switch ON.
    2. "(b) Clear the DTCs (see 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, and wait for at least 10 seconds.
    4. Turn the ignition switch ON.
    5. Check the DTCs (see DTC CHECK / CLEAR  ).

      OK: 

      DTC B1794 is not output. 

      HINT:

      DTCs other than B1794 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 FUSE (ECU-B) 
    1. Check the ECU-B fuse.

      Standard resistance: 

      Below 1 Ω 

    NG: REPLACE FUSE 

    OK: Go to next step 

  3. 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.

      OK: 

      The connectors are properly connected. 

    NG: CONNECT CONNECTOR 

    OK: Go to next step 

  4. CHECK WIRE HARNESS (SOURCE VOLTAGE) 
    1. Turn the ignition switch OFF.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Disconnect the L1 connector from the occupant classification ECU.
    4. Fig 1: Identifying L1 Connector Terminals
      G05585759Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    6. Measure the voltage of the wire harness side connector.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      L1-1 (+B) - Body ground Always 10 to 14 V
      L1-7 (IG) - Body ground Ignition switch ON 10 to 14 V
    7. Turn the ignition switch OFF.
    8. Measure the resistance of the wire harness side connector.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      L1-3 (GND) - Body ground Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR (BATTERY - OCCUPANT CLASSIFICATION ECU) 

    OK: Go to next step 

  5. CHECK FOR DTC 
    1. Turn the ignition switch OFF.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Connect the connectors to the occupant classification ECU.
    4. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    5. Turn the ignition switch ON.
    6. Clear the DTCs (see DTC CHECK / CLEAR  ).

      HINT:

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

    7. Turn the ignition switch OFF, and wait for at least 10 seconds.
    8. Turn the ignition switch ON.
    9. Using the Techstream, check for DTCs of the occupant classification ECU (see DTC CHECK / CLEAR  ).

      OK: 

      DTC B1794 is not output. 

      HINT:

      DTCs other than B1794 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 

  6. 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 (see REMOVAL  ).
  7. 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 ON.
    4. Using the Techstream, perform the zero point calibration (see INITIALIZATION  ).

      OK: 

      "Zero Point Calibration is complete." is displayed. 

  8. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform the sensitivity check (see INITIALIZATION  ).

      Standard value: 

      27 to 33 kg (59.52 to 72.75 lb) 

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