DTC    B1412/12    Ambient Temperature Sensor Circuit

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DESCRIPTION

The ambient temperature sensor is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner "AUTO" mode. The sensor connected to the ECM detects fluctuations in the ambient temperature. This data is used for controlling the room 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 read signal to the A/C amplifier via CAN and body multiplex communications.

DTC No.
DTC Detection Condition
Trouble Area
B1412/12
Open or short in ambient temperature sensor circuit
  1. Ambient temperature sensor
  2. Harness and connector between ambient temperature sensor and ECM
  3. ECM
  4. Multiplex communication circuit
  5. A/C amplifier

WIRING DIAGRAM


E109485E01


INSPECTION PROCEDURE

1.READ VALUE OF INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

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

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


A/C amplifier: 
Item
Measurement Item / Display
(Range)
Normal Condition
Diagnostic 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 displayed
Open in 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.


Result: 
NG
A
OK (Checking from the PROBLEM SYMPTOMS TABLE)
B
OK (Checking from the DTC)
C


B
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C
REPLACE AIR CONDITIONING AMPLIFIER
A


2.INSPECT AMBIENT TEMPERATURE SENSOR
E106870E01

  1. Remove the ambient temperature sensor.

  1. Measure the resistance of the sensor.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1 - 2
    		10°C (50°F)
    		3.00 to 3.73 kΩ
    1 - 2
    		15°C (59°F)
    		2.45 to 2.88 kΩ
    1 - 2
    		20°C (68°F)
    		1.95 to 2.30 kΩ
    1 - 2
    		25°C (77°F)
    		1.60 to 1.80 kΩ
    1 - 2
    		30°C (86°F)
    		1.28 to 1.47 kΩ
    1 - 2
    		35°C (95°F)
    		1.00 to 1.22 kΩ
    1 - 2
    		40°C (104°F)
    		0.80 to 1.00 kΩ
    1 - 2
    		45°C (113°F)
    		0.65 to 0.85 kΩ
    1 - 2
    		50°C (122°F)
    		0.50 to 0.70 kΩ
    1 - 2
    		55°C (131°F)
    		0.44 to 0.60 kΩ
    1 - 2
    		60°C (140°F)
    		0.36 to 0.50 kΩ

    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 (see the graph).



NG
REPLACE AMBIENT TEMPERATURE SENSOR
OK


3.CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - ECM)
E106871E02

  1. 3UZ-FE

    1. Disconnect the B5 ambient temperature sensor connector.

    2. Disconnect the A6 and E8 ECM connectors .

    3. Measure the resistance of the wire harness side connectors.

      Standard resistance:
      Tester Connection
      		Condition
      		Specified Condition
      B5-1 - A6-18 (TAM)
      		Always
      		Below 1 Ω
      B5-2 - E8-28 (E2)
      		Always
      		Below 1 Ω
      A6-18 (TAM) - Body ground
      		Always
      		10 kΩ or higher
      E8-28 (E2) - Body ground
      		Always
      		10 kΩ or higher



    E106872E02

  1. 3GR-FE, 3GR-FSE

    1. Disconnect the B5 ambient temperature sensor connector.

    2. Disconnect the A6 and E6 ECM connectors.

    3. Measure the resistance of the wire harness side connectors.

      Standard resistance:
      Tester Connection
      		Condition
      		Specified Condition
      B5-1 - A6-18 (TAM)
      		Always
      		Below 1 Ω
      B5-2 - E6-30 (E3)
      		Always
      		Below 1 Ω
      A6-18 (TAM) - Body ground
      		Always
      		10 kΩ or higher
      E6-30 (E3) - Body ground
      		Always
      		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE ECM