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Home >> Lexus >> 2008 >> IS 250 RWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 33 (Supplemental Restraint System) >> Airbag System >> DTC B1653/35 Seat Position Airbag Sensor Circuit Malfunction >> Inspection Procedure

Inspection Procedure

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK CONNECTORS 
    1. Turn the engine 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 center airbag sensor assembly, front seat inner belt assembly and the seat position airbag sensor

      OK: The connectors are properly connected. 

      HINT:

      If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection

    4. Disconnect the connectors from the center airbag sensor assembly, front seat inner belt assembly and the seat position airbag sensor.
    5. Check that the terminals of connectors are not damaged

      OK: The terminals are not deformed or damaged. 

    NG: REPLACE WIRE HARNESS 

    OK: Go to next step 

  2. CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT (OPEN) 
    1. Connect the connectors to the front seat inner belt assembly LH and No 2 floor wire.
    2. Using SST, connect terminals 14 (DSP+) and 13 (DSP-) of connector B
      NOTE: Do not forcibly insert SST into the terminals of the connector when connecting the wire.

      SST 09843-18040 

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

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      2 (LSP+) -1 (LSP-) Always Below 1 Ω
      4. Fig 1: Identifying Seat Position Airbag Sensor Circuit (Open)
      G05756981Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step  9

    OK: Go to next step 

  3. CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT (SHORT) 
    1. Disconnect SST from connector B
    2. Measure the resistance according to the value(s) in the table below

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      2 (LSP+) - 1 (LSP-) Always 1 MΩ or higher
      3. Fig 2: Identifying Seat Position Airbag Sensor Circuit (Short)
      G05756982Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step  10

    OK: Go to next step 

  4. CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT (SHORT TO B+) 
    1. Connect the cable to the negative (-) battery terminal
    2. Turn the engine switch on (IG)
    3. Measure the voltage according to the value(s) in the table below

      Standard Voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      2 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      1 (LSP-) - Body ground Engine switch on (IG) Below 1 V
      4. Fig 3: Identifying Seat Position Airbag Sensor Circuit (Short To B+)
      G05756983Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step  11

    OK: Go to next step 

  5. CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT (SHORT TO GROUND) 
    1. Turn the engine switch off
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      2 (LSP+) - Body ground Always 1 MΩ or higher
      1 (LSP-) - Body ground Always 1 MΩ or higher
      4. Fig 4: Identifying Seat Position Airbag Sensor Circuit (Short To Ground)
      G05756984Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step  12

    OK: Go to next step 

  6. CHECK SEAT POSITION AIRBAG SENSOR 
    1. Connect the connectors to the center airbag sensor assembly and the seat position airbag sensor.
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine switch on (IG), and wait for at least 60 seconds
    4. Clear the DTCs stored in the memory (See DTC CHECK / CLEAR  ).
    5. Turn the engine switch off
    6. Turn the engine switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs (See DTC CHECK / CLEAR  ).

      OK: DTC B1653/35 is not output. 

      HINT.

      Codes other than DTC B1653/35 may be output at this time, but they are not related to this check

      Fig 5: Identifying DLC3 Connector Terminals
      G05756985Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step 7 

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

  7. REPLACE SEAT POSITION AIRBAG SENSOR 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the seat position airbag sensor with a known good part (See REMOVAL  )

      HINT.

      Perform the following inspection using known good parts from another vehicle if possible.

  8. CHECK CENTER AIRBAG SENSOR ASSEMBLY 
    1. Connect the cable to the negative (-) battery terminal
    2. Turn the engine switch on (IG), and wait for at least 60 seconds.
    3. Clear the DTCs stored in the memory (See DTC CHECK / CLEAR  ).
    4. Turn the engine switch off.
    5. Turn the engine switch on (IG), and wait for at least 60 seconds
    6. Check for DTCs (See DTC CHECK / CLEAR  )

      OK: DTC B1653/35 is not output. 

      HINT:

      Codes other than DTC B1653/35 may be output at this time, but they are not related to this check.

      7. Fig 6: Identifying DLC3 Connector Terminals
      G05756986Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE CENTER AIRBAG SENSOR ASSEMBLY  (See REMOVAL  )

    OK: END 

  9. CHECK NO. 2 FLOOR WIRE (OPEN) 
    1. Disconnect the No. 2 floor wire from the front seat inner belt assembly LH.

      HINT

      SST has already been inserted into connector B

      Fig 7: Identifying No. 2 Floor Wire (Open)
      G05756987Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      Q6-2 (LSP+) - Q6-4 (LSP-) Always Below 1 Ω

    NG: REPLACE NO. 2 FLOOR WIRE 

    OK: REPLACE FRONT SEAT INNER BELT ASSEMBLY LH  (See REMOVAL )

  10. CHECK NO. 2 FLOOR WIRE (SHORT) 
    1. Disconnect the No 2 floor wire from the front seat belt inner belt assembly LH
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      Q6-2 (LSP+) - Q6-4 (LSP-) Always 1 MΩ or higher
      3. Fig 8: Identifying No. 2 Floor Wire (Short)
      G05756988Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE NO. 2 FLOOR WIRE 

    OK: REPLACE FRONT SEAT INNER BELT ASSEMBLY LH  (See REMOVAL )

  11. CHECK NO. 2 FLOOR WIRE (SHORT TO B+) 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Disconnect the No 2 floor wire from the front seat inner belt assembly LH
    4. Connect the cable to the negative (-) battery terminal.
    5. Turn the engine switch on (IG)
    6. Measure the voltage according to the value(s) in the table below

      Standard Voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      Q6-2 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      Q6-4 (LSP-) - Body ground Engine switch on (IG) Below 1 V
      7. Fig 9: Identifying No. 2 Floor Wire (Short To B+)
      G05756989Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE NO. 2 FLOOR WIRE 

    OK: REPLACE FRONT SEAT INNER BELT ASSEMBLY LH  (See REMOVAL )

  12. CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND) 
    1. Disconnect the No. 2 floor wire from the front seat inner belt assembly LH.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      Q6-2 (LSP+) - Body ground Always 1 MΩ or higher
      Q6-4 (LSP-) - Body ground Always 1 MΩ or higher
      3. Fig 10: Identifying No. 2 Floor Wire (Short To Ground)
      G05756990Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE NO. 2 FLOOR WIRE 

    OK: REPLACE FRONT SEAT INNER BELT ASSEMBLY LH  (See REMOVAL )

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