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Home >> Lexus >> 2007 >> GS 430 >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Air Conditioning >> Air Conditioning System >> DTC B1462/62 Room Humidity Sensor Circuit >> Inspection Procedure

Inspection Procedure

  1. READ VALUE OF INTELLIGENT TESTER 
    1. Connect the intelligent tester to the DLC3.
    2. Turn the engine switch on (IG) and push the intelligent tester main switch on.
    3. Select the item below in the Data List, and read the display on the intelligent tester.

    A/C amplifier: 

    DATA LIST CHART

    Item Measurement Item / Display (Range) Normal Condition Diagnostic Note
    HUMIDITY SENS
    (Humidity sensor)    		 Humidity Sensor /
    Min.: 0%, Max.: 100%    		 Actual room humidity is displayed -

    OK: 

    The display is as specified in the normal condition. 

    Result: 

    RESULT CHART

    NG A
    OK (Checking from the PROBLEM SYMPTOMS TABLE) B
    OK (Checking from the DTC) C

    B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE 

    C: REPLACE AIR CONDITIONING AMPLIFIER 

    A: Go to next step 

  2. CHECK WIRE HARNESS (ROOM TEMPERATURE SENSOR - A/C AMPLIFIER) 
    1. Disconnect the K33 room temperature sensor connector.
    2. Disconnect the K52 A/C amplifier connector.
    3. Measure the resistance of the wire harness side connectors.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      K33-3 (RH) - K52-15 (RH) Always Below 1 Ω
      K33-4 (S5) - K52-7 (S5-1) Always Below 1 Ω
      K33-2 (-) - K52-19 (SG-1) Always Below 1 Ω
      K52-19 (SG-1) - Body ground Always 10 kΩ or higher
      K52-15 (RH) - Body ground Always Below 1 Ω
      K52-7 (S5-1) - Body ground Always 10 kΩ or higher
    Fig 1: Identifying Room Temperature Sensor And A/C Amplifier Connector Terminals
    G05297778Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: Go to next step 

  3. CHECK AIR CONDITIONING AMPLIFIER 
    1. Remove the A/C amplifier with its connectors still connected.
    2. Measure the voltage of the connector.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      K52-7 (S5-1) - K52-19 (SG-1) Engine switch on (IG) 4.5 to 5.5 V
    Fig 2: Identifying Air Conditioning Amplifier Connector Terminals
    G05297779Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE AIR CONDITIONING AMPLIFIER 

    OK: Go to next step 

  4. CHECK ROOM HUMIDITY SENSOR 
    1. Remove the room temperature sensor.
    2. Measure the voltage of the sensor.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      2 (-) - 3 (RH) 10% 0.70 to 1.08 V
      2 (-) - 3 (RH) 20% 0.72 to 1.57 V
      2 (-) - 3 (RH) 30% 1.13 to 1.95 V
      2 (-) - 3 (RH) 40% 1.61 to 2.24 V
      2 (-) -3 (RH) 50% 1.99 to 2.46 V
      2 (-) - 3 (RH) 60% 2.26 to 2.66 V
      2 (-) - 3 (RH) 70% 2.48 to 2.85 V
      2 (-) - 3 (RH) 80% 2.68 to 3.04 V
      2 (-) - 3 (RH) 90% 2.87 to 3.05 V
    NOTE:
    • Do not touch the humidity sensor as body heat will affect the inspection results. When performing the inspection, hold the sensor by its connector.
    • Allow the sensor to acclimate to the ambient temperature and humidity before performing the inspection.
    • The standard voltages in the table above are based on inspections performed when the ambient temperature is 25°C (77°F).

    HINT:

    As the humidity increases, the resistance decreases (see the graph).

    Fig 3: Room Humidity Sensor Graph
    G05297780Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE ROOM HUMIDITY SENSOR 

    OK: REPLACE AIR CONDITIONING AMPLIFIER 

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