Heating Air Conditioning. Dtc B1423 Pressure Sensor Circuit

This DTC is output when refrigerant pressure on the high pressure side 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 A/C pressure sensor, installed on the high pressure line to detect refrigerant pressure, outputs a refrigerant pressure signal to the A/C amplifier. The A/C amplifier converts this signal to a pressure value according to the sensor characteristics to control the compressor.

DTC No.	DTC Detection Condition	Trouble Area
B1423	Open or short in A/C pressure sensor circuit Refrigerant pressure on the high pressure line 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).	A/C Pressure sensor Harness or connector between A/C pressure sensor and A/C amplifier A/C amplifier Expansion valve (blocked, stuck) Condenser (blocked, deterioration of cooling capacity due to dirt) Cooler dryer (moisture in the refrigerant cycle cannot be absorbed) Cooling fan system (condenser cannot be cooled down) A/C system (leaks, blocked)

WIRING DIAGRAM

Corolla. Zre142 Aze141.Heating Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System).
Dtc
B1423 Pressure Sensor Circuit

INSPECTION PROCEDURE

1.CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

Disconnect the connector from the A/C pressure sensor.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
A16-3 (+) - Body ground
Ignition switch ON
4.75 to 5.25 V
Text in Illustration
*a
Front view of wire harness connector
(to A/C Pressure Sensor)

Text in Illustration
*a	Front view of wire harness connector (to A/C Pressure Sensor)

Go to step 5

OK

2.CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
A16-1 (-) - Body ground
Always
Below 1 Ω
Text in Illustration
*a
Front view of wire harness connector
(to A/C Pressure Sensor)

Text in Illustration
*a	Front view of wire harness connector (to A/C Pressure Sensor)

Go to step 6

OK

3.INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

Reconnect the connector to the A/C pressure sensor.

Remove the A/C amplifier with the connectors still connected.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Condition
Specified Condition
E62-6 (PRE) - Body ground*1
Ignition switch ON
(A/C: OFF)
0.7 to 4.8 V
E111-12 (PRE) - Body ground*2
Ignition switch ON
(A/C: OFF)
0.7 to 4.8 V
1. *1: except TMC Made 2AZ-FE
2. *2: for TMC Made and except TMC Made 2ZR-FE
HINT:
If the measured voltage is not within the normal range, there may be a malfunction in the A/C amplifier, A/C pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.
Text in Illustration
*a
Component with wire harness connected
(A/C Amplifier (except TMC Made 2AZ-FE))
*b
Component with wire harness connected
(A/C Amplifier (for TMC Made and except TMC Made 2ZR-FE))

Text in Illustration
*a	Component with wire harness connected (A/C Amplifier (except TMC Made 2AZ-FE))
*b	Component with wire harness connected (A/C Amplifier (for TMC Made and except TMC Made 2ZR-FE))

Go to step 7

OK

4.INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

Measure the voltage when the following conditions are satisfied.

Item
Condition
Vehicle Doors
Fully open
Temperature Setting
MAX COLD
Blower Speed
HI
A/C Switch
ON
R/F Switch
RECIRCULATION
Interior Temperature
25 to 35°C (77 to 95°F)
Engine Speed
2000 rpm
NOTICE:
1. If refrigerant pressure on the high pressure line becomes extremely high during the inspection (if the voltage exceeds 4.8 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe function operates.
2. It is necessary to measure the voltage over a period 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 the 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
  Condition
  Specified Condition
  E62-6 (PRE) - Body ground*1
  Ignition switch ON
  (A/C: ON)
  0.7 to 4.8 V
  E111-12 (PRE) - Body ground*2
  Ignition switch ON
  (A/C: ON)
  0.7 to 4.8 V
  1. *1: except TMC Made 2AZ-FE
  2. *2: for TMC Made and except TMC Made 2ZR-FE
  Result:
  Result
  Proceed to
  OK (When troubleshooting according to DTC)
  A
  OK (When troubleshooting according to Problem Symptoms Table)
  B
  NG
  C
  Text in Illustration
  *a
  Component with wire harness connected
  (A/C Amplifier (except TMC Made 2AZ-FE))
  *b
  Component with wire harness connected
  (A/C Amplifier (for TMC Made and except TMC Made 2ZR-FE))

Text in Illustration
*a	Component with wire harness connected (A/C Amplifier (except TMC Made 2AZ-FE))
*b	Component with wire harness connected (A/C Amplifier (for TMC Made and except TMC Made 2ZR-FE))

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (COROLLA_ZRE142 RM000001M2W05PX.html)

Go to step 13

REPLACE AIR CONDITIONING AMPLIFIER (COROLLA_ZRE142 RM000002XMC01VX.html)

5.CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR)

Disconnect the connector from the A/C amplifier.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A16-3 (+) - E62-1 (S5-3)*1	Always	Below 1 Ω
E62-1 (S5-3) - Body ground*1	Always	10 kΩ or higher
A16-3 (+) - E111-7 (S5-3)*2	Always	Below 1 Ω
E111-7 (S5-3) - Body ground*2	Always	10 kΩ or higher

*1: except TMC Made 2AZ-FE
*2: for TMC Made and except TMC Made 2ZR-FE

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE AIR CONDITIONING AMPLIFIER (COROLLA_ZRE142 RM000002XMC01VX.html)

6.CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR)

Disconnect the connector from the A/C amplifier.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A16-1 (-) - E62-4 (SG-2)*1	Always	Below 1 Ω
E62-4 (SG-2) - Body ground*1	Always	10 kΩ or higher
A16-1 (-) - E111-10 (SG-2)*2	Always	Below 1 Ω
E111-10 (SG-2) - Body ground*2	Always	10 kΩ or higher

*1: except TMC Made 2AZ-FE
*2: for TMC Made and except TMC Made 2ZR-FE

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE AIR CONDITIONING AMPLIFIER (COROLLA_ZRE142 RM000002XMC01VX.html)

7.CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR)

Disconnect the connector from the A/C amplifier.

Disconnect the connector from the A/C pressure sensor.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A16-2 (PR) - E62-6 (PRE)*1	Always	Below 1 Ω
E62-6 (PRE) - Body ground*1	Always	10 kΩ or higher
A16-2 (PR) - E111-12 (PRE)*2	Always	Below 1 Ω
E111-12 (PRE) - Body ground*2	Always	10 kΩ or higher

*1: except TMC Made 2AZ-FE
*2: for TMC Made and except TMC Made 2ZR-FE

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

8.CHECK FOR A/C SYSTEM LEAK

Install the manifold gauge set.

Recover the refrigerant from the A/C system using a refrigerant recovery unit.

Evacuate the A/C system and check that vacuum can be maintained.
OK:
Vacuum can be maintained in the A/C system.
HINT:
If vacuum cannot be maintained in the A/C system, there may be a refrigerant leak. In this case, it is necessary to repair or replace the leaking part of the A/C system.

Go to step 12

OK

9.CHARGE REFRIGERANT

Add an appropriate amount of refrigerant (COROLLA_ZRE142 RM00000114604ZX_01_0002.html).

NEXT

10.RECHECK DTC

Recheck for DTCs when the following conditions are satisfied.

Item
Condition
Vehicle Doors
Fully open
Temperature Setting
MAX COLD
Blower Speed
HI
A/C Switch
ON
R/F Switch
RECIRCULATION
Interior Temperature
25 to 35°C (77 to 95°F)
Engine Speed
2000 rpm
NOTICE:
If refrigerant pressure on the high pressure line is excessive, this DTC will be set. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be set after the A/C has been operating for a while.
HINT:
When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
Result:
Result
Proceed to
DTC B1423 is output
A
DTC B1423 is not output
B
NOTICE:
If the DTC was set 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 leaks. The root cause of excessive refrigerant may be adding refrigerant when the level was insufficient. Therefore, identify and repair any refrigerant leaks as necessary.

END

A

11.INSPECT A/C PRESSURE SENSOR

Install the manifold gauge set.

Disconnect the connector from the A/C pressure sensor.

Connect the three 1.5 V dry cell batteries' positive (+) lead to terminal 3, and the negative (-) lead to terminal 1.

Connect the voltmeter's positive (+) lead to terminal 2, and the negative (-) lead to terminal 1.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Condition
Specified Condition
A16-2 (PR) - A16-1 (-)
Refrigerant pressure:
0.39 to 3.187 MPa (57 to 463 psi)
1.0 to 4.8 V
Text in Illustration
*a
Component without harness connected
(A/C Pressure Sensor)
*b
Voltage (V)
*c
Refrigerant Pressure (MPa (psi))

REPLACE A/C PRESSURE SENSOR (COROLLA_ZRE142 RM000003CY100FX.html)

REPLACE AIR CONDITIONING AMPLIFIER (COROLLA_ZRE142 RM000002XMC01VX.html)

12.REPAIR A/C SYSTEM LEAK

Identify the area where refrigerant leaks from (COROLLA_ZRE142 RM00000114604ZX_01_0004.html).

Repair the identified area of the A/C system.

Evacuate the A/C system.

CHARGE REFRIGERANT (COROLLA_ZRE142 RM00000114604ZX_01_0002.html)

13.INSPECT COOLING FAN SYSTEM

Check that the cooling fan operates normally.
HINT:
1. Cooling Fan Circuit (COROLLA_ZRE142 RM000002YZE03NX.html for 2AZ-FE).
2. Cooling Fan Circuit (COROLLA_ZRE142 RM000002WE9079X.html for 2ZR-FE).

REPAIR COOLING FAN SYSTEM

OK

14.CHARGE REFRIGERANT

Use a refrigerant recovery unit to recover refrigerant.

Evacuate the A/C system.

Add an appropriate amount of refrigerant (COROLLA_ZRE142 RM00000114604ZX_01_0002.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, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for DTCs.

NEXT

15.RECHECK DTC

Recheck for DTCs when the following conditions are satisfied.

Item
Condition
Vehicle Doors
Fully open
Temperature Setting
MAX COLD
Blower Speed
HI
A/C Switch
ON
R/F Switch
RECIRCULATION
Interior Temperature
25 to 35°C (77 to 95°F)
Engine Speed
2000 rpm
NOTICE:
If refrigerant pressure on the high pressure line is excessive, this DTC will be set. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because DTC may be set after the A/C has been operating for a while.
HINT:
1. When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the 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, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for DTCs. If the DTC is not output, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant. In this case, to complete the repair, it is necessary to replace the cooler dryer.
Result:
Result
Proceed to
DTC B1423 is output
A
DTC B1423 is not output
B

REPLACE COOLER DRYER (COROLLA_ZRE142 RM000002XLU067X.html)

A

16.REPLACE EXPANSION VALVE

Replace the expansion valve with a new one (COROLLA_ZRE142 RM000001HLX05GX.html).
HINT:
Replace the expansion valve with a normal one because the expansion valve is either stuck or clogged.

NEXT

17.CHARGE REFRIGERANT

Add an appropriate amount of refrigerant (COROLLA_ZRE142 RM00000114604ZX_01_0002.html).

NEXT

18.RECHECK DTC

Recheck for DTCs when the following conditions are satisfied.

Item
Condition
Vehicle Doors
Fully open
Temperature Setting
MAX COLD
Blower Speed
HI
A/C Switch
ON
R/F Switch
RECIRCULATION
Interior Temperature
25 to 35°C (77 to 95°F)
Engine Speed
2000 rpm
NOTICE:
If refrigerant pressure on the high pressure line is excessive, this DTC will be set. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be set after the A/C has been operating 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 the 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 one, the condenser or pipes may be clogged with dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes.
Result:
Result
Proceed to
DTC B1423 is not output
A
DTC B1423 is output
B

REPLACE CONDENSER (COROLLA_ZRE142 RM000002XLT04TX.html)

END

Tester Connection	Switch Condition	Specified Condition
A16-3 (+) - Body ground	Ignition switch ON	4.75 to 5.25 V

Item	Condition
Vehicle Doors	Fully open
Temperature Setting	MAX COLD
Blower Speed	HI
A/C Switch	ON
R/F Switch	RECIRCULATION
Interior Temperature	25 to 35°C (77 to 95°F)
Engine Speed	2000 rpm

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

Result	Proceed to
DTC B1423 is output	A
DTC B1423 is not output	B

*a	Component without harness connected (A/C Pressure Sensor)
*b	Voltage (V)
*c	Refrigerant Pressure (MPa (psi))