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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/ Auto A/C) - Diagnostic Codes (2 Of 2) >> AIR CONDITIONING SYSTEM (for Gasoline Model with Automatic Air Conditioning System) >> DTC B14B2-87: Lost Communication with Front Panel LIN Missing Message [11/2023 - ] >> Procedure

DTC B14B2-87: Lost Communication with Front Panel LIN Missing Message [11/2023 - ]: Procedure

  1. CONFIRM MODEL 

    Result

    Result Proceed to
    w/ Stop and Start System A
    w/o Stop and Start System B

    Result: 

    B 

    See step  8

    Result: 

    A 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - POWER SOURCE) 

    Pre-procedure1

    1. Disconnect the H27 air conditioning control assembly connector.

      Procedure1

    2. 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 10.5 to 16 V

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - BODY GROUND) 

    Pre-procedure1

    1. Disconnect the H27 air conditioning control assembly connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      H27-10 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONING CONTROL ASSEMBLY) 

    Pre-procedure1

    1. Disconnect the H27 air conditioning control assembly connector.
    2. Disconnect the H62 air conditioning amplifier assembly connector.

      Procedure1

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

      Standard Resistance

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

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (OUTPUT) 

    Pre-procedure1

    1. Disconnect the H27 air conditioning control assembly connector.
    2. Connect the H62 air conditioning amplifier assembly connector.

      Procedure1

    3. Using an oscilloscope, check the waveform.
      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.

      GTY829762Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 

    Refer to REMOVAL [11/2023 - ]

    Result: 

    OK 

    See step  6

  6. CHECK AIR CONDITIONING CONTROL ASSEMBLY (OUTPUT) 

    Pre-procedure1

    1. Connect the H27 air conditioning control assembly connector.

      Procedure1

    2. Using an oscilloscope, check the waveform.
      Item Content
      Tester Connection H27-8 (LIN1) - Body ground
      Tool Setting 2 V/DIV., 20 μs/DIV.
      Condition Ignition switch ON

      OK

      The waveform displays properly.

      GTY829762Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    OK 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 

    Refer to REMOVAL [11/2023 - ]

    Result: 

    NG 

    REPLACE AIR CONDITIONING CONTROL ASSEMBLY 

    Refer to REMOVAL [10/2022 - ]

  7. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - ENGINE STOP AND START ECU) 

    Pre-procedure1

    1. Disconnect the H27 air conditioning control assembly connector.
    2. Disconnect the H66 engine stop and start ECU connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      H27-6 (IG+) - H66-3 (IG41) Always Below 1 Ω
      H27-6 (IG+) or H66-3 (IG41) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    OK 

    GO TO STOP AND START SYSTEM (Backup Boost Converter Circuit) 

    Refer to Backup Boost Converter Circuit [11/2023 - ]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  8. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - AUXILIARY BATTERY) 

    Pre-procedure1

    1. Disconnect the H27 air conditioning control assembly connector.

      Procedure1

    2. 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

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. None

    Result: 

    OK 

    See step  3

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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