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Home >> Lexus >> 2017 >> CT 200h Base >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Occupant Classification System - Diagnostic Codes & Symptom Tests >> Occupant Classification System >> DTC B1794: Open in Occupant Classification ECU Battery Positive Line [08/2014 - ] >> Procedure

DTC B1794: Open in Occupant Classification ECU Battery Positive Line [08/2014 - ]: Procedure

  1. CHECK AUXILIARY BATTERY VOLTAGE 
    1. Measure the voltage of the auxiliary battery.

      Standard Voltage

      11 to 14 V

    Result:  NG

    NG 

    INSPECT AUXILIARY BATTERY 

    (Refer to On-Vehicle Inspection [08/2014 - ] )

    Result:  OK

    OK 

    Refer to  2

  2. CHECK WIRE HARNESS (SOURCE VOLTAGE) 
    1. Turn the power switch off.
      GTY528257Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Disconnect the connector from the occupant detection ECU.
    4. Connect the cable to the negative (-) auxiliary battery terminal.
    5. Turn the power switch on (IG).
    6. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      W4-1 (+B) - Body ground Always 11 to 14 V
    7. Turn the power switch off.
    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      W4-3 (GND) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Occupant Detection ECU)

    Result:  NG

    NG 

    REPLACE WIRE HARNESS 

    Result:  OK

    OK 

    Refer to  3

  3. CHECK DTC 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Connect the connector to the occupant detection ECU.
    4. Connect the cable to the negative (-) auxiliary battery terminal.
    5. Turn the power switch on (IG).
    6. Clear the DTCs stored in the occupant detection ECU (Refer to DTC Check / Clear [08/2014 - ] ).
    7. Clear the DTCs stored in the airbag sensor assembly (Refer to DTC Check / Clear [08/2014 - ] ).
    8. Turn the power switch off.
    9. Turn the power switch on (IG), and wait for at least 10 seconds.
    10. Check for DTCs (Refer to DTC Check / Clear [08/2014 - ] ).

      OK

      DTC B1794 is not output.

      HINT: 

      Codes other than DTC B1794 may be output at this time, but they are not related to this check.

    Result:  OK

    OK 

    USE SIMULATION METHOD TO CHECK 

    (Refer to How To Proceed With Troubleshooting [08/2014 - ] )

    Result:  NG

    NG 

    Refer to  4

  4. REPLACE OCCUPANT DETECTION ECU 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
    3. Replace the occupant detection ECU (Refer to Removal [08/2014 - ] ).

    Result:  NEXT

    NEXT 

    Refer to  5

  5. PERFORM ZERO POINT CALIBRATION 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
    2. Turn the power switch on (IG).
    3. Using the Techstream, perform Zero Point Calibration (Refer to Initialization [08/2014 - ] ).

    Result:  NEXT

    NEXT 

    Refer to  6

  6. PERFORM SENSITIVITY CHECK 
    1. Using the Techstream, perform Sensitivity Check (Refer to Initialization [08/2014 - ] ).

    Result:  NEXT

    NEXT 

    END 

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