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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating / Air Conditioning System (Except HV, W/ Manual A/C) - Diagnostic Codes, Circuit Tests & Symptom Tests >> AIR CONDITIONING SYSTEM (for Gasoline Model with Manual Air Conditioning System) >> DTC B14B2: Lost Communication with Front Panel LIN [12/2019 - 10/2022] >> Procedure

DTC B14B2: Lost Communication with Front Panel LIN [12/2019 - 10/2022]: Procedure

  1. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - BATTERY AND BODY GROUND) 
    1. Disconnect the H27 air conditioning control assembly connector.
    2. Measure the resistance according to the value(s) in the table below.
      GTY873762Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioning Control Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition
      H27-10 (GND) - Body ground Always Below 1 Ω
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      H27-6 (IG+) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONING CONTROL ASSEMBLY) 
    1. Disconnect the H62 air conditioning amplifier assembly connector.
    2. Disconnect the H27 air conditioning control assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H62-7 (LIN1) - H27-8 (LIN1) Always Below 1 Ω
      H62-7 (LIN1) or H27-8 (LIN1) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (OUTPUT) 
    1. Connect the H62 air conditioning amplifier assembly connector.
    2. Disconnect the H27 air conditioning control assembly connector.
    3. Using an oscilloscope, check the waveform.
      GTY933589Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -
      Item Content
      Tester Connection H62-7 (LIN1) - Body ground
      Tool Setting 2 V/DIV., 20 μs/DIV.
      Condition Ignition switch ON

      OK

      The waveform displays properly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING CONTROL ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022] 

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