Dtc B1412/12 Ambient Temperature Sensor Circuit


DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE USING INTELLIGENT TESTER (AMBIENT TEMPERATURE SENSOR)

INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR)

CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)

DTC B1412/12 Ambient Temperature Sensor Circuit


DESCRIPTION

The cooler thermistor (ambient temperature sensor) is installed in the front part of the cooler condenser assembly to detect the ambient temperature and control the air conditioning auto mode. The sensor connected to the air conditioning amplifier assembly detects fluctuations in the ambient temperature. This data is used for controlling the room temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the cooler thermistor (ambient temperature sensor) changes in accordance with the cooler thermistor temperature (ambient temperature). As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The air conditioning amplifier assembly applies a voltage (5 V) to the cooler thermistor (ambient temperature sensor) and reads voltage changes as changes in the resistance of the cooler thermistor (ambient temperature sensor).

DTC Code
DTC Detection Condition
Trouble Area
B1412/12
An open or short in the cooler thermistor (ambient temperature sensor) circuit.
  1. Cooler thermistor (ambient temperature sensor)
  2. Harness or connector
  3. Air conditioning amplifier assembly

WIRING DIAGRAM


Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.Heating Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc B1412/12 Ambient Temperature Sensor Circuit


INSPECTION PROCEDURE

1.READ VALUE USING INTELLIGENT TESTER (AMBIENT TEMPERATURE SENSOR)

  1. Use the Data List to check if the cooler thermistor (ambient temperature sensor) is functioning properly (LandCruiser RM000002LIV040X.html).

    Air Conditioner
    Tester Display
    		Measurement Item/Range
    		Normal Condition
    		Diagnostic Note
    Ambient Temp Sensor
    		Cooler thermistor (ambient temperature sensor) /
    Min: -23.3°C (-9.94°F)
    Max: 65.95°C (150.71°F)
    		Actual ambient temperature displayed
    		Open in the circuit: -23.3°C (-9.94°F).
    Short in the circuit: 65.95°C (150.71°F).
    OK:
    The display is as specified in the normal condition column.
    Result
    Result
    		Proceed to
    OK (When troubleshooting according to problem symptoms table)
    		A
    OK (When troubleshooting according to the DTC)
    		B
    NG
    		C


B
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (LandCruiser RM0000039R5028X.html)

C
Go to step 2
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (LandCruiser RM0000045E302NX.html)

2.INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR)


    Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.Heating Air Conditioning.Air Conditioning System (For Automatic Air Conditioning System). Dtc B1412/12 Ambient Temperature Sensor Circuit

  1. Remove the cooler thermistor (ambient temperature sensor) (LandCruiser RM000002VYK03HX.html).

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1 - 2
    		10°C (50°F)
    		3.00 to 3.73 kΩ
    15°C (59°F)
    		2.45 to 2.88 kΩ
    20°C (68°F)
    		1.95 to 2.30 kΩ
    25°C (77°F)
    		1.60 to 1.80 kΩ
    30°C (86°F)
    		1.28 to 1.47 kΩ
    35°C (95°F)
    		1.00 to 1.22 kΩ
    40°C (104°F)
    		0.80 to 1.00 kΩ
    45°C (113°F)
    		0.65 to 0.85 kΩ
    50°C (122°F)
    		0.50 to 0.70 kΩ
    55°C (131°F)
    		0.44 to 0.60 kΩ
    60°C (140°F)
    		0.36 to 0.50 kΩ
    Text in Illustration
    *a
    		Sensing Portion
    *b
    		Resistance
    *c
    		Allowable Range
    *d
    		Temperature
    NOTICE:
    1. Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
    2. When measuring, the sensor temperature must be the same as the ambient temperature.
    HINT:
    As the temperature increases, the resistance decreases (refer to the graph).


NG
REPLACE COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR) (LandCruiser RM000002VYK03HX.html)
OK


3.CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)

  1. Disconnect the A1 sensor connector.

  1. Disconnect the G25 amplifier connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A1-1 - G25-5 (TAM)
    		Always
    		Below 1 Ω
    A1-2 - G25-13 (SG-2)
    G25-5 (TAM) - Body ground
    		Always
    		10 kΩ or higher
    G25-13 (SG-2) - Body ground


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY (LandCruiser RM0000039R5028X.html)