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Home >> Lexus >> 2007 >> LS 460L >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Air Conditioning >> Air Conditioning System >> DTC B1423/23 Pressure Sensor Circuit >> Inspection Procedure

Inspection Procedure

  1. CHECK REFRIGERANT 
    Fig 1: Identifying Sight Glass
    G04950402Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Check the sight glass on the liquid pipe.
      1. Prepare the vehicle according to the chart below.
        SIGHT GLASS ON LIQUID PIPE

        Item Condition
        Vehicle Doors Fully open
        Temperature Setting MAX COLD
        Blower Speed HI
        A/C ON
        Engine switch on (IG)
      2. Compare the sight glass to the following chart.
        COMPARING SIGHT GLASS

        Item Symptom Amount of Refrigerant Corrective Actions
        1 Bubbles visible Insufficient
        1. Check for gas leakage and repair if necessary
        2. Add refrigerant until bubbles disappear
        2 No bubbles visible Empty, insufficient or excessive Refer to 3 and 4
        3 No temperature difference between compressor inlet and outlet Empty or nearly empty
        1. Check for gas leakage with halogen leak detector and repair if necessary
        2. Evacuate A/C system and recharge proper amount of refrigerant
        4 Considerable temperature difference between compressor inlet and outlet Proper or excessive Refer to 5 and 6
        5 Immediately after air conditioning is turned OFF, refrigerant clears Excessive
        1. Discharge refrigerant
        2. Evacuate A/C system and recharge proper amount of refrigerant
        6 Immediately after air conditioning is turned OFF, refrigerant foams and then becomes clear Proper -
        HINT:
        *: Bubbles in the sight glass with the vehicle interior above 35°C (95°F) can be considered normal if cooling is sufficient.

    NG: CHARGE REFRIGERANT (See  REPLACEMENT   ) 

    OK: GO TO NEXT STEP 

  2. READ VALUE OF INTELLIGENT TESTER OR TECHSTREAM (REFRIGERANT PRESSURE SENSOR) 
    1. Use the Data List to check if the refrigerant pressure sensor is functioning properly.
      1. Intelligent tester

        AIR CONDITIONER 

        INTELLIGENT TESTER - AIR CONDITIONER REFERENCE CHART

        Tester Display Measurement Item / Range Normal Condition Diagnostic Note
        REG PRESS SENS Refrigerant pressure sensor /
        Min.: 0 kgf/cm2 G
        Max.: 38.25 kgf/cm2 G        		 Actual refrigerant pressure is displayed -
      2. Techstream

        Air conditioner 

        TECHSTREAM - AIR CONDITIONER REFERENCE CHART

        Tester Display Measurement Item / Range Normal Condition Diagnostic Note
        Regulator Pressure Sensor Refrigerant pressure sensor /
        Min.: 0 kgf/cm2 G
        Max.: 38.25 kgf/cm2 G        		 Actual refrigerant pressure is displayed -

        OK: The display is as specified in the normal condition. 

        Result 

        RESULT CHART

        Result Proceed to
        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 (See  PROBLEM SYMPTOMS TABLE   ) 

    C: REPLACE AIR CONDITIONING AMPLIFIER (See  REMOVAL   ) 

    A: GO TO NEXT STEP 

  3. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - FRONT LIGHT ECU) 
    Fig 2: Checking Harness And Connector (Pressure Sensor - Front Light ECU)
    G04950403Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the B4 pressure sensor connector.
    2. Disconnect the B14 front light ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      PRESSURE SENSOR - FRONT LIGHT ECU

      Tester Connection Condition Specified Condition
      B4-2 (PR) - B14-13 (PRS) Always Below 1 Ω
      B4-3(+)-B14-12(S5) Always Below 1 Ω
      B4-1(-)-B14-14(SG) Always Below 1 Ω
      B14-13 (PRS) -Body ground Always 10 kΩ or higher
      B14-12(S5)-Body ground Always 10 kΩ or higher
      B14-14(SG)-Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: GO TO NEXT STEP 

  4. CHECK FRONT LIGHT ECU 
    Fig 3: Checking Front Light ECU Connectors
    G04950404Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the front light ECU with its connectors still connected.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      FRONT LIGHT ECU RESISTANCE

      Tester Connection Condition Specified Condition
      B14-14 (SG) - Body ground Always Below 1 Ω
    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      FRONT LIGHT ECU VOLTAGE

      Tester Connection Switch Condition Specified Condition
      B14-12 (S5) - B14-14 (SG) Engine switch on (IG) 4.5 to 5.5 V
      Engine switch off Below 1 V

    NG: REPLACE FRONT LIGHT ECU 

    OK: GO TO NEXT STEP 

  5. CHECK PRESSURE SENSOR 
    Fig 4: Checking Pressure Sensor
    G04950405Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Install the manifold gauge set.
    2. Connect the three 1.5 V dry cell batteries' positive (+) lead to terminal 3 and the negative (-) lead to terminal 1. Then connect the voltmeter's positive (+) lead to terminal 2 and the negative (-) lead to terminal 1. Measure the voltage.

      OK: The voltage changes according to refrigerant pressure, as shown in the graph. 

    NG: REPLACE PRESSURE SENSOR 

    OK: REPLACE FRONT LIGHT ECU 

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