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Home >> Lexus >> 2020 >> ES 300h Luxury >> Repair and Diagnosis >> External Pages >> Different car >> Section 219 (Heating / Air Conditioning System (Except Hybrid) - Diagnostic Codes & Symptom Tests) >> AIR CONDITIONING SYSTEM (for Gasoline Model) >> DTC B1412: Ambient Temperature Sensor Circuit [06/2018 - ] >> Procedure

DTC B1412: Ambient Temperature Sensor Circuit [06/2018 - ]: Procedure

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2024 Lexus ES 350, 2024 Lexus ES 250, 2023 Lexus ES 350, 2023 Lexus ES 250, and 2022 Lexus ES 350. However, it is still accessible from the selected car via links, so may be relevant.
  1. READ VALUE USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.
    5. Read the Data List according to the display on the Techstream.

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Ambient Temp Sensor Thermistor assembly Min.: -23.30°C (-9.94°F)
      Max.: 65.95°C (150.71°F)      		 Actual ambient temperature displayed Thermistor assembly circuit malfunction
      • When open circuit: -23.30°C (-9.94°F)
      • When short circuit: 65.95°C (150.71°F)

      Body Electrical > Air Conditioner > Data List 

      Tester Display
      Ambient Temp Sensor

      OK

      The display is as specified in the normal condition column.

      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 

    See step  2

  2. INSPECT THERMISTOR ASSEMBLY 
    1. Remove the thermistor assembly.

      Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]

    2. Inspect the thermistor assembly.

      Refer to INSPECTION [06/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE THERMISTOR ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - 09/2022]  , or refer to  REMOVAL [09/2022 - ] 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (THERMISTOR ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the G40 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
      A20-2 - G40-13 (TAM) Always Below 1 Ω
      A20-1 - G40-2 (SG-2) Always Below 1 Ω
      A20-2 or G40-13 (TAM) - Other terminals and body ground Always 10 kΩ or higher
      A20-1 or G40-2 (SG-2) - Other terminals and body ground Always 10 kΩ or higher

      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 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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