B1423

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1423/23: Pressure Sensor Circuit
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.

HINT
* 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.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK REFRIGERANT

(a) Check the sight glass on the liquid pipe.

(1) Prepare the vehicle according to the chart below.

(2) Compare the sight glass to the following chart.

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 Service and Repair
OK -- Continue to next step.

2. READ VALUE USING TECHSTREAM (REFRIGERANT PRESSURE SENSOR)

(a) Use the Data List to check if the refrigerant pressure sensor is functioning properly.

Air Conditioner

OK:

The display is as specified in the normal condition.

Result

B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

C -- REPLACE AIR CONDITIONING AMPLIFIER Removal
A -- Continue to next step.

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

(a) Disconnect the B4 pressure sensor connector.

(b) Disconnect the B14 front light ECU connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. CHECK FRONT LIGHT ECU

(a) Remove the front light ECU with its connectors still connected.

(b) Measure the resistance according to the value(s) in the table below.

Standard resistance:

NG -- REPLACE FRONT LIGHT ECU
OK -- Continue to next step.

5. CHECK PRESSURE SENSOR

(a) Install the manifold gauge set.

(b) 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