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Home >> Lexus >> 2021 >> ES 250 Luxury >> Repair and Diagnosis >> Accessories & Equipment >> Seats >> Seat Heater System (Except Hybrid) - Diagnostic Codes & Symptom Tests >> SEAT HEATER SYSTEM (for Gasoline Model) >> DTC B14B5: Lost Communication with Front Seat Temperature Adjustment Switch LIN [06/2018 - ] >> Procedure

DTC B14B5: Lost Communication with Front Seat Temperature Adjustment Switch LIN [06/2018 - ]: Procedure

  1. CLEAR DTC 
    1. Clear the DTCs.

      Body Electrical > Air Conditioner > Clear DTCs 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  2

  2. CHECK FOR DTC 
    1. Check for DTCs.

      Body Electrical > Air Conditioner > Trouble Codes 

      OK

      DTC B14B5 is not output.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ] 

    Result: 

    NG 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - REFRESHING SEAT SWITCH AND BODY GROUND) 
    1. Disconnect the G35 refreshing seat switch connector.
      GTY822141Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Refreshing Seat Switch)
    2. Measure the voltage and resistance according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G35-10 (IG) - Body ground Engine switch on (IG) 11 to 14 V
      G35-10 (IG) - Body ground Engine switch off Below 1 V

      Standard Resistance

      Tester Connection Condition Specified Condition
      G35-6 (E) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - REFRESHING SEAT SWITCH) 
    1. Disconnect the G39 air conditioning amplifier assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G39-14 (LIN1) - G35-8 (SW) Always Below 1 Ω
      G39-14 (LIN1) or G35-8 (SW) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Connect the G39 air conditioning amplifier assembly connector.
      GTY786479Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Turn the engine switch on (IG).
    3. Using an oscilloscope, check the waveform.

      OK

      Waveform is similar to that shown in the illustration.

      Item Content
      Terminal No. G39-14 (LIN1) - Body ground
      Tool Setting 2 V/DIV., 20 ms./DIV.
      Condition Engine switch on (IG)

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - ] 

    Result: 

    OK 

    See step  6

  6. INSPECT REFRESHING SEAT SWITCH 
    1. Connect the G35 refreshing seat switch connector.
      GTY809283Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Refreshing Seat Switch)
    2. Turn the engine switch on (IG).
    3. Using an oscilloscope, check the waveform.
      Item Content
      Terminal No. G35-8 (SW) - Body ground
      Tool Setting 2 V/DIV., 20 ms./DIV.
      Condition Engine switch on (IG)

      OK

      Waveform is similar to that shown in the illustration.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - ] 

    Result: 

    NG 

    REPLACE REFRESHING SEAT SWITCH 

    Refer to REMOVAL [06/2018 - ]

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