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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) - Circuit Tests & Symptom Tests >> AIR CONDITIONING SYSTEM (for Gasoline Model with Automatic Air Conditioning System) >> PTC Heater Circuit [12/2019 - 11/2023] >> Procedure

PTC Heater Circuit [12/2019 - 11/2023]: Procedure

  1. INSPECT PTC HTR RELAYS 

    Refer to ON-VEHICLE INSPECTION [12/2019 - 11/2023]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE PTC HTR RELAY 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE - PTC HTR RELAYS) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      PTC HTR NO. 1 

      Tester Connection Condition Specified Condition
      3 (PTC HTR NO. 1 relay) - Body ground Ignition switch off 11 to 14 V
      2 (PTC HTR NO. 1 relay) - Body ground Ignition switch off Below 1 V
      2 (PTC HTR NO. 1 relay) - Body ground Ignition switch ON 11 to 14 V

      Standard Voltage

      PTC HTR NO. 2 

      Tester Connection Condition Specified Condition
      3 (PTC HTR NO. 2 relay) - Body ground Ignition switch off 11 to 14 V
      2 (PTC HTR NO. 2 relay) - Body ground Ignition switch off Below 1 V
      2 (PTC HTR NO. 2 relay) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (PTC HTR RELAYS - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the H62 and H63 air conditioning amplifier assembly connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      PTC HTR NO. 1 

      Tester Connection Condition Specified Condition
      1 (PTC HTR NO. 1 relay) - H62-23 (PTC1) Always Below 1 Ω
      1 (PTC HTR NO. 1 relay) or H62-23 (PTC1) - Body ground Always 10 kΩ or higher

      Standard Resistance

      PTC HTR NO. 2 

      Tester Connection Condition Specified Condition
      1 (PTC HTR NO. 2 relay) - H63-16 (PTC2) Always Below 1 Ω
      1 (PTC HTR NO. 2 relay) or H63-16 (PTC2) - 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. CHECK HARNESS AND CONNECTOR (PTC HTR RELAYS - QUICK HEATER ASSEMBLY AND BODY GROUND) 
    1. Disconnect the G3 and G4 quick heater assembly connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      PTC HTR NO. 1 

      Tester Connection Condition Specified Condition
      5 (PTC HTR NO. 1 relay) - G3-2 (B) Always Below 1 Ω
      5 (PTC HTR NO. 1 relay) - G4-1 (B) Always Below 1 Ω
      5 (PTC HTR NO. 1 relay) or G3-2 (B) - Other terminals and body ground Always 10 kΩ or higher
      5 (PTC HTR NO. 1 relay) or G4-1 (B) - Other terminals and body ground Always 10 kΩ or higher

      Standard Resistance

      PTC HTR NO. 2 

      Tester Connection Condition Specified Condition
      5 (PTC HTR NO. 2 relay) - G4-3 (B) Always Below 1 Ω
      5 (PTC HTR NO. 2 relay) or G4-3 (B) - 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  5

  5. INSPECT QUICK HEATER ASSEMBLY 

    Refer to INSPECTION [12/2019 - 11/2023]

    Result

    Proceed to
    OK
    NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    NG 

    REPLACE QUICK HEATER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

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