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Home >> Lexus >> 2017 >> LS 460 Base, AWD >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System - Diagnostic Codes & Symptom Tests >> Occupant Classification System >> DTC B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction [09/2015 - ] >> Procedure

DTC B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction [09/2015 - ]: Procedure

  1. CHECK FOR DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    3. Clear the DTCs stored in the center airbag sensor (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Check for the DTCs (Refer to DTC CHECK / CLEAR [09/2015 - ] ).

      OK

      DTC B1790 is not output.

      HINT: 

      Codes other than DTC B1790 may be output at this time, but they are not related to this check.

    Result:  OK

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [09/2015 - ] )

    Result:  NG

    NG 

    See step  2

  2. CHECK CONNECTION OF CONNECTOR 
    1. Turn the engine switch off.
    2. Disconnect the negative (-) terminal cable from the battery.
    3. Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor.

      OK

      Connectors are properly connected.

    Result:  NG

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result:  OK

    OK 

    See step  3

  3. CHECK CONNECTOR 
    1. Disconnect the connectors from the center airbag sensor and the occupant classification ECU.
    2. Check that the connectors (on the center airbag sensor side and occupant classification ECU side) are not damaged.

      OK

      Connectors are not deformed or damaged.

    Result:  NG

    NG 

    REPLACE HARNESS OR CONNECTOR 

    Result:  OK

    OK 

    See step  4

  4. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT 
    1. Connect the negative (-) terminal cable to the battery.
      GTY637943Courtesy 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 Switch Condition Specified Condition
      e10-11 (FSR+) - Body ground Engine switch on (IG) Below 1 V
      e10-12 (FSR-) - Body ground
    4. Turn the engine switch off.
    5. Disconnect the negative (-) terminal cable from the battery.
    6. Using a service wire, connect terminals 16 (FSR+) and 22 (FSR-) of connector B.
      NOTE:

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

    7. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      e10-11 (FSR+) - e10-12 (FSR-) Always Below 1 Ω
    8. Disconnect the service wire from connector B.
    9. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      e10-11 (FSR+) - e10-12 (FSR-) Always 1 MΩ or higher
      e10-11 (FSR+) - Body ground
      e10-12 (FSR-) - Body ground

    Result:  NG

    NG 

    See step  10

    Result:  OK

    OK 

    See step  5

  5. CHECK FOR DTC 
    1. Connect the connectors to the occupant classification ECU and the center airbag sensor.
    2. Connect the Techstream to the DLC3.
    3. Connect the negative (-) terminal cable to the battery.
    4. Turn the engine switch on (IG).
    5. Clear the DTCs stored in the occupant classification ECU (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    6. Clear the DTCs stored in the center airbag sensor (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    7. Turn the engine switch off.
    8. Turn the engine switch on (IG).
    9. Using the Techstream, check for the DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [09/2015 - ] ).

      OK

      DTC B1790 is not output.

      HINT: 

      Codes other than DTC B1790 may be output at this time, but they are not related to this check.

    Result:  OK

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to DIAGNOSIS SYSTEM [09/2015 - ] )

    Result:  NG

    NG 

    See step  6

  6. REPLACE FRONT SEAT CUSHION ASSEMBLY (OCCUPANT CLASSIFICATION ECU) 
    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 was installed on the vehicle (Refer to REGISTRATION [09/2015 - ] ).
    4. Turn the engine switch off.
    5. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
    6. Replace the front seat cushion assembly (occupant classification ECU) (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    7. Connect the negative (-) terminal cable to the battery.
    8. Turn the engine switch on (IG).
    9. Using the Techstream, load the previous ECU data stored in the Techstream into the new ECU (Refer to REGISTRATION [09/2015 - ] ).
    10. Turn the engine switch off.
    11. Turn the engine switch on (IG).
    12. Clear the DTCs stored in the memory (Refer to DTC CHECK / CLEAR [09/2015 - ] ).

      HINT: 

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

    Result:  NEXT

    NEXT 

    See step  7

  7. CHECK FOR DTC 
    1. Turn the engine switch on (IG).
    2. Clear the DTCs stored in the occupant classification ECU (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    3. Clear the DTCs stored in the center airbag sensor (Refer to DTC CHECK / CLEAR [09/2015 - ] ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG).
    6. Using the Techstream, check for the DTCs of the occupant classification ECU (Refer to DTC CHECK / CLEAR [09/2015 - ] ).

      OK

      DTC B1790 is not output.

      HINT: 

      Codes other than DTC B1790 may be output at this time, but they are not related to this check.

    Result:  OK

    OK 

    See step  9

    Result:  NG

    NG 

    See step  8

  8. REPLACE CENTER AIRBAG SENSOR ASSEMBLY 
    1. Turn the engine switch off.
    2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
    3. Replace the center airbag sensor (Refer to REMOVAL [09/2015 - ] ).

    Result:  NEXT

    NEXT 

    See step  9

  9. PERFORM SENSITIVITY CHECK 
    1. Perform the sensitivity check (Refer to INITIALIZATION [09/2015 - ] ).

    Result:  NEXT

    NEXT 

    END 

  10. CHECK FLOOR WIRE 
    1. Turn the engine switch off.
      GTY641920Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
    3. Disconnect the front seat wire RH connector from the floor wire.
    4. Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
    5. Turn the engine switch on (IG).
    6. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Switch Condition Specified Condition
      Re3-2 (FSR+) - Body ground Engine switch on (IG) Below 1 V
      Re3-3 (FSR-) - Body ground
    7. Disconnect the front seat wire RH connector from the floor wire.
    8. Disconnect the negative (-) terminal cable from the battery.
    9. Using service wire, connect terminals 16 (FSR+) and 22 (FSR-) of connector B.
      NOTE:

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

    10. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      Re3-2 (FSR+) - Re3-3 (FSR-) Always Below 1 Ω
    11. Disconnect the service wire from connector B.
    12. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      Re3-2 (FSR+) - Re3-3 (FSR-) Always 1 MΩ or higher
      Re3-2 (FSR+) - Body ground
      Re3-3 (FSR-) - Body ground

    Result:  OK

    OK 

    REPLACE FRONT SEAT WIRE RH 

    Result:  NG

    NG 

    REPLACE FLOOR WIRE 

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