Lexus IS250 IS220d GSE20 ALE20 - AIR CONDITIONING

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK ENGINE TYPE

CHECK MULTIPLEX COMMUNICATION SYSTEM

CHECK CAN COMMUNICATION SYSTEM

READ VALUE OF INTELLIGENT TESTER

INSPECT AMBIENT TEMPERATURE SENSOR

CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - ECM)

READ VALUE OF INTELLIGENT TESTER

INSPECT AMBIENT TEMPERATURE SENSOR

CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - A/C AMPLIFIER)

DTC B1412/12 Ambient Temperature Sensor Circuit

DESCRIPTION

4GR-FSE:
The ambient temperature sensor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioner "AUTO" mode. This sensor is connected to the ECM and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the A/C amplifier via the ECM. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The ECM applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes. The ECM sends the signal to the A/C amplifier via CAN and body multiplex communication.
2AD-FHV:
The ambient temperature sensor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioner "AUTO" mode. This sensor is connected to the A/C amplifier and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the A/C amplifier. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The A/C amplifier applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes.
DTC No.DTC Detection ConditionTrouble Area
B1412/12Open or short in ambient temperature sensor circuit
4GR-FSE:
Ambient temperature sensor
Harness and connector between ambient temperature sensor and ECM
ECM
Multiplex communication circuit
A/C amplifier
2AD-FHV:
Ambient temperature sensor
Harness or connector between ambient temperature sensor and A/C amplifier
A/C amplifier

WIRING DIAGRAM

Dtc B1412/12 Ambient Temperature Sensor Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

Dtc B1412/12 Ambient Temperature Sensor Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

1.CHECK ENGINE TYPE

Check the engine type.

  • Result:
  • ResultProceed to
    4GR-FSE
    (Gasoline engine)    		A
    2AD-FHV
    (Diesel engine)    		B
B
Go to step 7
A
2.CHECK MULTIPLEX COMMUNICATION SYSTEM

Use the intelligent tester to check if the Multiplex Communication System (MPX) is functioning normally.

  • Result:
  • ResultProceed to
    MPX DTC is not outputA
    MPX DTC is outputB
B
GO TO MULTIPLEX COMMUNICATION SYSTEM
A
3.CHECK CAN COMMUNICATION SYSTEM

Use the intelligent tester to check if the CAN Communication System is functioning normally.

  • Result:
  • ResultProceed to
    CAN DTC is not outputA
    CAN DTC is outputB
B
GO TO CAN COMMUNICATION SYSTEM
A
4.READ VALUE OF INTELLIGENT TESTER

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) and turn the intelligent tester main switch on.

Select the item below in the Data List, and read the display on the intelligent tester.

Data List / Air Conditioner:
ItemMeasurement Item / Display (Range)Normal ConditionDiagnostic Note
Ambient Temp Sensor
(Ambi Temp Sens)		Ambient temperature sensor / Min: -23.3°C (-9.94°F), Max: 65.95°C (150.71°F)Actual ambient temperature is displayedOpen in circuit: -23.3°C (-9.94°F)
Short in circuit: 65.95°C (150.71°F)
  • OK:
  • The display is as specified in the normal condition column.
  • Result:
  • ResultProceed to
    NGA
    OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE)B
    OK (When troubleshooting according to the DTC)C
B
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C
REPLACE AIR CONDITIONING AMPLIFIER
A
5.INSPECT AMBIENT TEMPERATURE SENSOR
Dtc B1412/12 Ambient Temperature Sensor Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

Remove the ambient temperature sensor.

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

  • Standard resistance:
  • Tester ConnectionConditionSpecified Condition
    B5-1 - B5-210°C (50°F)3.00 to 3.73 kΩ
    B5-1 - B5-215°C (59°F)2.45 to 2.88 kΩ
    B5-1 - B5-220°C (68°F)1.95 to 2.30 kΩ
    B5-1 - B5-225°C (77°F)1.60 to 1.80 kΩ
    B5-1 - B5-230°C (86°F)1.28 to 1.47 kΩ
    B5-1 - B5-235°C (95°F)1.00 to 1.22 kΩ
    B5-1 - B5-240°C (104°F)0.80 to 1.00 kΩ
    B5-1 - B5-245°C (113°F)0.65 to 0.85 kΩ
    B5-1 - B5-250°C (122°F)0.50 to 0.70 kΩ
    B5-1 - B5-255°C (131°F)0.44 to 0.60 kΩ
    B5-1 - B5-260°C (140°F)0.36 to 0.50 kΩ
  • NOTICE:
Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
When measuring, the sensor temperature must be the same as the ambient temperature.
  • HINT:
  • As the temperature increases, the resistance decreases (see the graph).
NG
REPLACE AMBIENT TEMPERATURE SENSOR
OK
6.CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - ECM)
Dtc B1412/12 Ambient Temperature Sensor Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

Disconnect the ambient temperature sensor connector.

Disconnect the ECM connectors.

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

  • Standard resistance:
  • Tester ConnectionConditionSpecified Condition
    B5-1 - A5-18 (TAM)AlwaysBelow 1 Ω
    B5-2 - E5-30 (E3)AlwaysBelow 1 Ω
    A5-18 (TAM) - Body groundAlways10 kΩ or higher
    E5-30 (E3) - Body groundAlways10 kΩ or higher
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE ECM
7.READ VALUE OF INTELLIGENT TESTER

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) and turn the intelligent tester main switch on.

Select the item below in the Data List, and read the display on the intelligent tester.

Data List / Air Conditioner:
ItemMeasurement Item / Display (Range)Normal ConditionDiagnostic Note
Ambient Temp Sensor
(Ambi Temp Sens)		Ambient temperature sensor / Min: -23.3°C (-9.94°F), Max: 65.95°C (150.71°F)Actual ambient temperature is displayedOpen in circuit: -23.3°C (-9.94°F)
Short in circuit: 65.95°C (150.71°F)
  • OK:
  • The display is as specified in the normal condition column.
  • Result:
  • ResultProceed to
    NGA
    OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE)B
    OK (When troubleshooting according to the DTC)C
B
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
C
REPLACE AIR CONDITIONING AMPLIFIER
A
8.INSPECT AMBIENT TEMPERATURE SENSOR
Dtc B1412/12 Ambient Temperature Sensor Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

Remove the ambient temperature sensor.

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

  • Standard resistance:
  • Tester ConnectionConditionSpecified Condition
    B5-1 - B5-210°C (50°F)3.00 to 3.73 kΩ
    B5-1 - B5-215°C (59°F)2.45 to 2.88 kΩ
    B5-1 - B5-220°C (68°F)1.95 to 2.30 kΩ
    B5-1 - B5-225°C (77°F)1.60 to 1.80 kΩ
    B5-1 - B5-230°C (86°F)1.28 to 1.47 kΩ
    B5-1 - B5-235°C (95°F)1.00 to 1.22 kΩ
    B5-1 - B5-240°C (104°F)0.80 to 1.00 kΩ
    B5-1 - B5-245°C (113°F)0.65 to 0.85 kΩ
    B5-1 - B5-250°C (122°F)0.50 to 0.70 kΩ
    B5-1 - B5-255°C (131°F)0.44 to 0.60 kΩ
    B5-1 - B5-260°C (140°F)0.36 to 0.50 kΩ
  • NOTICE:
Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
When measuring, the sensor temperature must be the same as the ambient temperature.
  • HINT:
  • As the temperature increases, the resistance decreases (see the graph).
NG
REPLACE AMBIENT TEMPERATURE SENSOR
OK
9.CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - A/C AMPLIFIER)
Dtc B1412/12 Ambient Temperature Sensor Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

Disconnect the ambient temperature sensor connector.

Disconnect the A/C amplifier connector.

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

  • Standard resistance:
  • Tester ConnectionConditionSpecified Condition
    B5-1 - J58-36 (TAM)AlwaysBelow 1 Ω
    B5-2 - J58-37 (SG)AlwaysBelow 1 Ω
    J58-36 (TAM) - Body groundAlways10 kΩ or higher
    J58-37 (SG) - Body groundAlways10 kΩ or higher
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
REPLACE AIR CONDITIONING AMPLIFIER
LEXUS IS250, IS220d / GSE20 ALE20
AIR CONDITIONING
Lexus IS250 IS220d GSE20 ALE20
AIR CONDITIONING SYSTEM