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Home >> Lexus >> 2008 >> LX 570 >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Restraint System >> Occupant Classification System >> DTC B1797 Calibration Malfunction >> Inspection Procedure

Inspection Procedure

NOTE:
  • w/ Navigation system:

    After the engine switch is turned off, the HDD navigation system requires approximately 6 minutes to record various types of memory and settings. As a result, after turning the engine switch off, wait 6 minutes or more before disconnecting the cable from the negative (-) battery terminal.

  • When disconnecting the cable from the negative (-) battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected (See INITIALIZATION ).
  1. CHECK FOR DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU (See DTC CHECK / CLEAR  ).
    3. Clear the DTCs stored in the center airbag sensor (See DTC CHECK/CLEAR  ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG), and wait for at least 10 seconds.
    6. Check for DTCs (See DTC CHECK / CLEAR  ).

      OK: DTC B1797 is not output. 

      HINT:

      Codes other than DTC B1797 may be output at this time, but they are not related to this check.

    NG: Go to step 2 

    OK: USE SIMULATION METHOD TO CHECK  (See DIAGNOSIS SYSTEM  )

  2. READ VALUE USING TECHSTREAM (SPECIFIED CONDITION FOR ZERO POINT CALIBRATION) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using the Techstream, read the "Data List" (See DATA LIST / ACTIVE TEST  )

      Occupant Detection 

      DIAGNOSTIC NOTE NORMAL CONDITION CHART

      Tester Display Measurement Item/ Range Normal Condition Diagnostic Note
      Pressure sensor output Pressure sensor output / Min 0, Max 255 0 to 210 (reference value) -
      Thermistor temperature output Thermistor temperature output / Min -40°C (-40°F), Max 90°C (194°F) -40 to 85°C (-40 to 185°F) If the value is outside the range of Specified Condition for Zero Point Calibration, check whether any objects are placed on the seat cushion and that the seat cushion is fitted correctly
      Number of Present DTC Number of stored trouble codes / Min 0, Max 255 0 -
      Number of Past DTC Number of past trouble codes / Min.. 0, Max 255 0 -

      Result 

      RESULT CHART

      Result Proceed to
      All items correspond to range of specified condition for zero point calibration A
      Thermistor temperature output does not correspond to range of specified condition for zero point calibration B

    B:  Go to step  5

    A: Go to Next Step 

  3. PERFORM ZERO POINT CALIBRATION 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using the Techstream, perform zero point calibration (See INITIALIZATION  )
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Clear the DTCs stored in the memory (See DTC CHECK / CLEAR  ).

      HINT:

      If the DTCs are not cleared at this time, past DTCs will remain.

  4. CHECK FOR DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU (See DTC CHECK / CLEAR  ).
    3. Clear the DTCs stored in the center airbag sensor (See DTC CHECK/CLEAR  ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check for DTCs (See DTC CHECK / CLEAR  ).

      OK: DTC B1797 is not output. 

      HINT:

      Codes other than DTC B1797 may be output at this time, but they are not related to this check.

    NG: Go to step 5 

    OK: END 

  5. REPLACE NO. 1 SEAT CUSHION ASSEMBLY (OCCUPANT DETECTION SENSOR) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using the Techstream, save the ECU data from the ECU which is installed in the vehicle (See REGISTRATION  ).
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Replace the No. 1 seat cushion (occupant detection sensor) (See DISASSEMBLY ).
    7. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    8. Turn the engine switch on (IG).
    9. Using the Techstream, load the previous ECU data stored in the Techstream into the new ECU (See REGISTRATION  ).
    10. Turn the engine switch off.
    11. Turn the engine switch on (IG).
    12. Clear the DTCs stored in the occupant classification ECU (See DTC CHECK / CLEAR  ).
    13. Clear the DTCs stored in the center airbag sensor (See DTC CHECK/CLEAR  ).
  6. PERFORM ZERO POINT CALIBRATION 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Using the Techstream, perform zero point calibration (See INITIALIZATION  )
    4. Turn the engine switch off
    5. Turn the engine switch on (IG).
    6. Clear the DTCs stored in the occupant classification ECU (See DTC CHECK / CLEAR  ).

      HINT.

      If the DTCs are not cleared at this time, past DTCs will remain.

  7. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check (See INITIALIZATION  ).

    NEXT: END 

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