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Home >> Lexus >> 2021 >> UX 200 Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Seats >> Seat Heater System (Diagnostic Codes & Symptom Tests) >> Seat Heater System >> DTC B14B5: Lost Communication with Front Seat Temperature Adjustment Switch LIN [07/2022 - ] >> Procedure

DTC B14B5: Lost Communication with Front Seat Temperature Adjustment Switch LIN [07/2022 - ]: Procedure

  1. CHECK FOR DTC 
    1. Check for DTCs.

      Body Electrical > Air Conditioner > Trouble Codes 

      OK

      DTC B14B5 is not output.

      Result

        Proceed to
      Only DTC B14B5 is output A
      DTC B14B2, B14B5 and B14B7 are output B

    Result: 

    B 

    GO TO AIR CONDITIONING SYSTEM (B14B2). Refer to  DTC B14B2: Lost Communication with Front Panel LIN [07/2022 - ] 

    Result: 

    A 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - REFRESHING SEAT SWITCH - BODY GROUND) 
    1. Disconnect the refreshing seat switch connector.
      GTY1131233Courtesy 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 Switch Condition Specified Condition
      F138-1 (IG) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V

      Standard Resistance

      Tester Connection Condition Specified Condition
      F138-5 (E) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - REFRESHING SEAT SWITCH) 
    1. Disconnect the F51 air conditioning amplifier assembly connector.
    2. Disconnect the F138 refreshing seat switch connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F51-14 (LIN1) - F138-3 (CN2+) Always Below 1 Ω
      F51-14 (LIN1) or F138-3 (CN2+) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Connect the air conditioning amplifier assembly connector.
      GTY800663Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)
    2. Turn the ignition switch to ON.
    3. Using an oscilloscope, check the waveform.
      Item Content
      Terminal No. F51-14 (LIN1) - Body ground
      Tool Setting 2 V/DIV., 20 ms./DIV.
      Condition Ignition switch ON

      OK

      Waveform is similar to that shown in the illustration.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    OK 

    See step  5

  5. INSPECT REFRESHING SEAT SWITCH 
    1. Connect the refreshing seat switch connector.
      GTY1132699Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Refreshing Seat Switch)
    2. Turn the ignition switch to ON.
    3. Using an oscilloscope, check the waveform.
      Item Content
      Terminal No. F138-3 (CN2+) - Body ground
      Tool Setting 2 V/DIV., 20 ms./DIV.
      Condition Ignition switch ON

      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 [07/2022 - ] 

    Result: 

    NG 

    REPLACE REFRESHING SEAT SWITCH. Refer to  REMOVAL [07/2022 - ] 

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