AIR CONDITIONING SYSTEM, Diagnostic DTC:B1423/23

DTC Code DTC Name
B1423/23 Pressure Sensor Circuit

DESCRIPTION

This DTC is output when refrigerant pressure is extremely low (0.19 MPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm2, 455 psi) or more). The pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the front light ECU (front controller). The front light ECU (front controller) sends the read signal to the air conditioning amplifier via the CAN communication line. The air conditioning amplifier converts the signals to pressure according to the sensor characteristics to control the compressor.

Tech Tips


  • Be sure to check the refrigerant volume first when this DTC is output because this DTC can also be output if there is no refrigerant in the cycle.

  • This circuit uses the CAN communication line. Before performing the inspection, check that the CAN communication system is functioning normally.

DTC No. DTC Detection Condition Trouble Area
B1423/23 Open or short in pressure sensor circuit

  • Pressure sensor

  • Harness and connector between pressure sensor and front light ECU (front controller)

  • Front light ECU (front controller)

  • Refrigerant pipe line

  • CAN communication line

  • Air conditioning amplifier

WIRING DIAGRAM

A001C1CE03

PROCEDURE


  1. CHECK REFRIGERANT

    A001DO9E01
    *1 Sight Glass

    1. Check the sight glass on the liquid pipe.


      1. Prepare the vehicle according to the chart below.

        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.

      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 -

      Tech Tips

      *: 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 Click here

    OK

  2. READ VALUE USING INTELLIGENT TESTER (REFRIGERANT PRESSURE SENSOR)


    1. Use the Data List to check if the refrigerant pressure sensor is functioning properly.

      Air Conditioner
      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Regulator Pressure Sensor

      Refrigerant pressure sensor /

      Min.: -0.4566 MPa

      Max.: 3.2943 MPa

      		 Actual refrigerant pressure is displayed -
      OK
      The display is as specified in the normal condition.
      Result
      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 Click here

    C

    REPLACE AIR CONDITIONING AMPLIFIER Click here

    A

  3. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - FRONT LIGHT ECU)

    A001B20E05
    *1 Front view of wire harness connector: (to Pressure Sensor)
    *2 Front view of wire harness connector: (to Front Light ECU)
    *3 PRS

    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
      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

  4. CHECK FRONT LIGHT ECU

    A001F74E03

    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
      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
      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

  5. CHECK PRESSURE SENSOR

    A001BJIE02

    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.

    OK

    REPLACE FRONT LIGHT ECU

    NG

    REPLACE PRESSURE SENSOR