Heating Air Conditioning. Dtc B1423 Pressure Sensor Circuit

This DTC is stored when refrigerant pressure is extremely low (0.176 MPa [1.8 kgf/cm2, 25.5 psi] or less) or extremely high (3.03 MPa [30.9 kgf/cm2, 439.4 psi] or higher). The air conditioner pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts the signal to a pressure value 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 may also be stored if there is no refrigerant in the cycle.

DTC No.	DTC Detection Condition	Trouble Area
B1423	Either condition is met: An open or short in the air conditioner pressure sensor circuit. Refrigerant pressure on the high pressure side is extremely low or extremely high.	Air conditioner pressure sensor Harness or connector Cooler expansion valve Cooler condenser assembly Cooler dryer Refrigerant pipe line Air conditioning amplifier assembly Amount of Refrigerant (too much or Insufficient) Cooling fan system

WIRING DIAGRAM

Yaris. Ncp93, 131.Heating Air Conditioning.Air Conditioning System (For Sedan).
Dtc
B1423 Pressure Sensor Circuit

INSPECTION PROCEDURE

1.CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

Disconnect the A60 air conditioner pressure sensor connector.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
A60-3 (+) - Body ground
Ignition switch ON
4.75 to 5.25 V
Text in Illustration
*a
Front view of wire harness connector
(to Air Conditioner Pressure Sensor)

Text in Illustration
*a	Front view of wire harness connector (to Air Conditioner Pressure Sensor)

Go to step 5

OK

2.CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)

Disconnect the A60 air conditioner pressure sensor connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
A60-1 (-) - Body ground
Always
Below 1 Ω
Text in Illustration
*a
Front view of wire harness connector
(to Air Conditioner Pressure Sensor)

Text in Illustration
*a	Front view of wire harness connector (to Air Conditioner Pressure Sensor)

Go to step 6

OK

3.CHECK AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

Reconnect the air conditioner pressure sensor connector.

Remove the air conditioning amplifier assembly with its connectors still connected (YARIS_NCP93 RM00000214000EX.html).

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
D130-7 (PRE) - Body ground
Ignition switch ON
A/C switch off
0.63 to 4.73 V
Text in Illustration
*a
Component with harness connected
(Air Conditioning Amplifier Assembly)
HINT:
If the measured voltage is not within the normal range, there may be a malfunction in the air conditioning amplifier assembly, air conditioner pressure sensor or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

Text in Illustration
*a	Component with harness connected (Air Conditioning Amplifier Assembly)

Go to step 7

OK

4.CHECK AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

Measure the voltage when the following conditions are met.
Measurement Condition
Item
Condition
Engine Speed
1500 rpm
Vehicle Doors
Fully open
Temperature Setting
MAX COOL
Blower Speed
HI
A/C Switch
ON
R/F Switch
Recirculation
Interior Temperature
25 to 35°C (77 to 95°F)
NOTICE:
1. If refrigerant pressure on the high pressure side becomes extremely high during the inspection (the voltage exceeds 4.8 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe operation.
2. It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the problem symptom may recur after a while.
HINT:
When the outside air temperature is low (below -1.5°C [29.3°F]), the compressor stops due to operation of the ambient temperature sensor and evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
1. Measure the voltage according to the value(s) in the table below.
  Standard Voltage:
  Tester Connection
  Switch Condition
  Specified Condition
  D130-7 (PRE) - Body ground
  Ignition switch ON
  A/C switch on
  0.63 to 4.73 V
  Text in Illustration
  *a
  Component with harness connected
  (Air Conditioning Amplifier Assembly)
  Result
  Result
  Proceed to
  OK (When troubleshooting according to the DTC)
  A
  OK (When troubleshooting according to Problem Symptoms Table)
  B
  NG
  C

Measurement Condition
Item	Condition
Engine Speed	1500 rpm
Vehicle Doors	Fully open
Temperature Setting	MAX COOL
Blower Speed	HI
A/C Switch	ON
R/F Switch	Recirculation
Interior Temperature	25 to 35°C (77 to 95°F)

Text in Illustration
*a	Component with harness connected (Air Conditioning Amplifier Assembly)

Result
Result	Proceed to
OK (When troubleshooting according to the DTC)	A
OK (When troubleshooting according to Problem Symptoms Table)	B
NG	C

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (YARIS_NCP93 RM000001M2W05EX.html)

Go to step 13

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (YARIS_NCP93 RM00000214000EX.html)

5.CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

Disconnect the A60 air conditioner pressure sensor connector.

Disconnect the D130 air conditioning amplifier assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
A60-3 (+) - D130-24 (S5- 3)
Always
Below 1 Ω
A60-3 (+) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (YARIS_NCP93 RM00000214000EX.html)

6.CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

Disconnect the A60 air conditioner pressure sensor connector.

Disconnect the D130 air conditioning amplifier assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
A60-1 (-) - D130-5 (SG-2)
Always
Below 1 Ω
A60-1 (-) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (YARIS_NCP93 RM00000214000EX.html)

7.CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

Disconnect the A60 air conditioner pressure sensor connector.

Disconnect the D130 air conditioning amplifier assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
A60-2 (PR) - D130-7 (PRE)
Always
Below 1 Ω
A60-2 (PR) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

8.CHECK FOR AIR CONDITIONING SYSTEM LEAK

Install a manifold gauge set.

Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.

Evacuate the air conditioning system and check that vacuum can be maintained in it.
OK:
Vacuum can be maintained in the air conditioning system.
HINT:
If vacuum cannot be maintained in the air conditioning system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the air conditioning system.

Go to step 12

OK

9.CHARGE REFRIGERANT

Add an appropriate amount of refrigerant (YARIS_NCP93 RM000000R57024X.html).

NEXT

10.CHECK FOR DTC

Check for DTCs when the following conditions are met (YARIS_NCP93 RM000001GUF06ZX.html).
Measurement Condition
Item
Condition
Engine Speed
1500 rpm
Vehicle Doors
Fully open
Temperature Setting
MAX COOL
Blower Speed
HI
A/C Switch
ON
R/F Switch
Recirculation
Interior Temperature
25 to 35°C (77 to 95°F)
NOTICE:
If refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system operates for a while.
HINT:
When the outside air temperature is low (below -1.5°C [29.3°F]), the compressor stops due to operation of the ambient temperature sensor and evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
OK:
DTC B1423 is not output
NOTICE:
If the DTC was stored due to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leakage. Therefore, identify and repair the area where refrigerant leaks as necessary. The root cause of excessive refrigerant may be adding too much refrigerant.

Go to step 11

END

11.INSPECT AIR CONDITIONER PRESSURE SENSOR

Inspect the air conditioner pressure sensor (YARIS_NCP93 RM000000VUG020X.html).

Go to step 19

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (YARIS_NCP93 RM00000214000EX.html)

12.REPAIR AIR CONDITIONING SYSTEM LEAK

Identify the area where refrigerant leaks (YARIS_NCP93 RM000000R58024X.html).

Repair the identified area of the air conditioning system.

Evacuate the air conditioning system.

CHARGE REFRIGERANT (YARIS_NCP93 RM000000R57024X.html)

13.CHECK COOLING FAN SYSTEM

Check that the cooling fan(s) operates normally.
HINT:
Refer to Cooling Fan Circuit (YARIS_NCP93 RM000002U52033X.html).

REPAIR COOLING FAN SYSTEM

OK

14.CHARGE REFRIGERANT

Use a refrigerant recovery unit to recover refrigerant.

Evacuate the air conditioning system.

Add an appropriate amount of refrigerant (YARIS_NCP93 RM000000R57024X.html).
HINT:
If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and then check for the DTC.

NEXT

15.CHECK FOR DTC

Check for DTCs when the following conditions are met (YARIS_NCP93 RM000001GUF06ZX.html).
Measurement Condition
Item
Condition
Engine Speed
1500 rpm
Vehicle Doors
Fully open
Temperature Setting
MAX COOL
Blower Speed
HI
A/C Switch
ON
R/F Switch
Recirculation
Interior Temperature
25 to 35°C (77 to 95°F)
NOTICE:
If refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system operates for a while.
HINT:
1. When the outside air temperature is low (below -1.5°C [29.3°F]), the compressor stops due to operation of the ambient temperature sensor and evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
2. If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant and check for the DTC. If the DTC is not output after this procedure, it indicates that the cooler dryer in the cooler condenser assembly is not able to absorb moisture in the refrigerant cycle. In this case, to complete the repair, it is necessary to replace the cooler dryer.
OK:
DTC B1423 is output

REPLACE COOLER DRYER (YARIS_NCP93 RM00000213T00LX.html)

OK

16.REPLACE COOLER EXPANSION VALVE

Replace the cooler expansion valve with a new or normally functioning one (YARIS_NCP93 RM000004P6V004X.html).
HINT:
Replace the cooler expansion valve with a new or normally functioning one because the cooler expansion valve is either stuck or clogged.

NEXT

17.CHARGE REFRIGERANT

Add an appropriate amount of refrigerant (YARIS_NCP93 RM000000R57024X.html).

NEXT

18.CHECK FOR DTC

Check for DTCs when the following conditions are met (YARIS_NCP93 RM000001GUF06ZX.html).
Measurement Condition
Item
Condition
Engine Speed
1500 rpm
Vehicle Doors
Fully open
Temperature Setting
MAX COOL
Blower Speed
HI
A/C Switch
ON
R/F Switch
Recirculation
Interior Temperature
25 to 35°C (77 to 95°F)
NOTICE:
If refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system operates for a while.
HINT:
1. When the outside air temperature is low (below -1.5°C [29.3°F]), the compressor stops due to operation of the ambient temperature sensor and evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
2. If refrigerant pressure is not normal after replacing the expansion valve with a new or normally functioning one, the cooler condenser assembly or pipes may be clogged due to dirt, dust or other contaminants. In this case, clean or replace the cooler condenser assembly or pipes.
OK:
DTC B1423 is not output

CLEAN OR REPLACE COOLER CONDENSER ASSEMBLY WITH RECEIVER OR PIPES (YARIS_NCP93 RM000003TSJ007X.html)

END

19.REPLACE AIR CONDITIONER PRESSURE SENSOR

Replace the air conditioner pressure sensor (YARIS_NCP93 RM000003E0T00CX.html).

NEXT

20.CHECK FOR DTC

Check for DTCs when the following conditions are met (YARIS_NCP93 RM000001GUF06ZX.html).
Measurement Condition
Item
Condition
Engine Speed
1500 rpm
Vehicle Doors
Fully open
Temperature Setting
MAX COOL
Blower Speed
HI
A/C Switch
ON
R/F Switch
Recirculation
Interior Temperature
25 to 35°C (77 to 95°F)
NOTICE:
If refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system operates for a while.
HINT:
When the outside air temperature is low (below -1.5°C [29.3°F]), the compressor stops due to operation of the ambient temperature sensor and evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
OK:
DTC B1423 is not output

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (YARIS_NCP93 RM00000214000EX.html)

END

Tester Connection	Switch Condition	Specified Condition
A60-3 (+) - Body ground	Ignition switch ON	4.75 to 5.25 V