Toyota Tacoma (2015-2018) Service Manual: Pressure Sensor Circuit (B1423/23)

Toyota Tacoma (2015-2018) Service Manual / Air Conditioning / Air Conditioning System(for Automatic Air Conditioning System) / Pressure Sensor Circuit (B1423/23)

DESCRIPTION

This DTC is stored if refrigerant pressure on the high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less) or extremely high (3140 kPa (32.0 kgf/cm2, 455 psi) or more). The air conditioner pressure sensor, which is installed on the pipe on the high pressure side to detect refrigerant pressure, sends a refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts this signal to a pressure value according to the sensor characteristics and uses it to control the compressor.

DTC No.	DTC Detection Condition	Trouble Area
B1423/23	Open or short in air conditioning pressure sensor circuit Refrigerant pressure on the high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less) or extremely high (3140 kPa (32.0 kgf/cm2, 455 psi) or more).	Air conditioner pressure sensor Harness or connector Air conditioning amplifier assembly Cooler expansion valve (blocked, stuck) Cooler condenser assembly (blocked, deterioration of cooling capacity due to dirt) Cooler dryer (moisture in the refrigerant cycle cannot be absorbed) Cooling fan system (cooler condenser assembly cannot be cooled down) A/C system (leaks, blocked)

WIRING DIAGRAM

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the A34 air conditioner pressure sensor connector.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A34-3 (+) - Body ground	Ignition switch ON	4.75 to 5.25 V

GO TO STEP 5

2.	CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)

(a) Disconnect the A34 air conditioner pressure sensor connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A34-1 (-) - Body ground	Always	Below 1 Ω

GO TO STEP 6

3.	INSPECT AIR CONDITIONING PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Reconnect the A34 air conditioner pressure sensor connector.

(b) Remove the air conditioning amplifier assembly with the connectors still connected (See page ).

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A35-2 (PRE) - Body ground	Ignition switch ON (A/C: off)	0.74 to 4.71 V

Tester Connection

Switch Condition

Specified Condition

A35-2 (PRE) - Body ground

Ignition switch ON

(A/C: off)

0.74 to 4.71 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 conditioning pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

GO TO STEP 7

4.	INSPECT AIR CONDITIONING PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) 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:

If refrigerant pressure on the high pressure side 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 operation.
It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the malfunction 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
A35-2 (PRE) - Body ground	Refer to above "Procedure Condition"	0.74 to 4.71 V

Text in Illustration

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

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

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

GO TO STEP 13

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

(a) Reconnect the A34 air conditioner pressure sensor connector.

(b) Disconnect the A35 air conditioning amplifier assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A34-3 (+) - A36-12 (S5-1)	Always	Below 1 Ω
A34-3 (+) or A36-12 (S5-1) - Body ground	Always	10 kΩ or higher

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

(a) Reconnect the A34 air conditioner pressure sensor connector.

(b) Disconnect the A36 air conditioning amplifier assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A34-1 (-) - A36-28 (SG-8)	Always	Below 1 Ω
A34-1 (-) or A36-28 (SG-8) - Body ground	Always	10 kΩ or higher

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

(a) Reconnect the A34 air conditioner pressure sensor connector.

(b) Disconnect the A35 air conditioning amplifier assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A34-2 (PR) - A35-2 (PRE)	Always	Below 1 Ω
A34-2 (PR) or A35-2 (PRE) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	INSPECT FOR A/C SYSTEM LEAK

(a) Install a manifold gauge set.

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

OK:

Vacuum can be maintained in the A/C system.

HINT:

If vacuum cannot be maintained in the A/C system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the A/C system.

GO TO STEP 12

9.	CHARGE SYSTEM WITH REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the A/C system.

for HFC-134a(R134a) (See page )
for HFO-1234yf(R1234yf) (See page )

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 cooler 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 DTCs.

10.	RECHECK FOR DTC

(a) 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 side becomes high, the DTC will be set. It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C operates for a while.

HINT:

Result	Proceed to
DTC B1423/23 is output	A
DTC B1423/23 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 too much refrigerant when the level was insufficient. Therefore, identify and repair the area where refrigerant leaks from as necessary.

END

11.	INSPECT AIR CONDITIONER PRESSURE SENSOR

(a) Install a manifold gauge set.

(b) Reconnect the A34 air conditioner pressure sensor connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A35-2 (PRE) - A36-28 (SG-8)

Refrigerant pressure:

(less than 3140 kPa (32.0 kgf/cm2, 455 psi) and more than 176 kPa (1.8 kgf/cm2, 26 psi))

0.74 to 4.71 V

Text in Illustration

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

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

REPLACE AIR CONDITIONING PRESSURE SENSOR

12.	REPAIR A/C SYSTEM LEAK

(a) Identify the area where refrigerant leaks from.

for HFC-134a(R134a) (See page )
for HFO-1234yf(R1234yf) (See page )

(b) Repair the identified area of the A/C system.

Result	Proceed to
for HFC-134a(R134a)	A
for HFO-1234yf(R1234yf)	B

CHARGE SYSTEM WITH REFRIGERANT

13.	INSPECT COOLING FAN SYSTEM

(a) Check that the cooling fan(s) operates normally.

HINT:

Refer to cooling fan system (See page ).

GO TO COOLING FAN SYSTEM

14.	CHARGE SYSTEM WITH REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the A/C system.

for HFC-134a(R134a) (See page )
for HFO-1234yf(R1234yf) (See page )

HINT:

15.	RECHECK FOR DTC

(a) 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:

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.
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 cooler 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 work, it indicates that the cooler dryer in the cooler condenser assembly is not able to absorb moisture in the refrigerant cycle. It is necessary to replace the cooler dryer in order to complete the repair.

Result	Proceed to
DTC B1423/23 is output	A
DTC B1423/23 is not output	B

REPLACE COOLER CONDENSER ASSEMBLY

16.	REPLACE COOLER EXPANSION VALVE

(a) Replace the cooler expansion valve with a new one (See page HINT: ).

HINT:

Replace the cooler expansion valve with a new one because the cooler expansion valve is either stuck or clogged.

17.	CHARGE SYSTEM WITH REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the A/C system.

for HFC-134a(R134a) (See page )
for HFO-1234yf(R1234yf) (See page )

HINT:

18.	RECHECK FOR DTC

(a) 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:

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.
If refrigerant pressure is not normal after replacing the cooler expansion valve with a new or known good one, the condenser or pipes may be clogged due to dirt, dust or other foreign matter. In this case, clean or replace the cooler condenser assembly or pipes.

Result	Proceed to
DTC B1423/23 is not output	A
DTC B1423/23 is output	B

END

CLEAN OR REPLACE COOLER CONDENSER ASSEMBLY OR PIPE

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