AIR CONDITIONING SYSTEM(for Automatic Air Conditioning System), Diagnostic DTC:B1412/12

DTC Code DTC Name
B1412/12 Ambient Temperature Sensor Circuit

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 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 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 air conditioning amplifier assembly applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes.

DTC Code DTC Detection Condition Trouble Area
B1412/12 An open or short in the ambient temperature sensor circuit.

  • Ambient temperature sensor

  • Harness or connector between ambient temperature sensor and air conditioning amplifier assembly

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A01X64TE38
w/ Rear Heater
*a Ambient Temperature Sensor
*b Air Conditioning Amplifier Assembly
A01X64TE39
w/o Rear Heater
*a Ambient Temperature Sensor
*b Air Conditioning Amplifier Assembly

PROCEDURE


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


    1. Use the Data List to check if the ambient temperature sensor is functioning properly.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Ambient Temp Sensor

      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.

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

  2. INSPECT AMBIENT TEMPERATURE SENSOR

    A01X1LIE01

    1. Remove the ambient temperature sensor Click here.

    2. 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

      Note


      • 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.

      Tech Tips

      As the temperature increases, the resistance decreases (see the graph).


    NG

    REPLACE AMBIENT TEMPERATURE SENSOR Click here

    OK

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

    A01X4EJE01
    *a Front view of wire harness connector: (to Ambient Temperature Sensor)
    *b Rear view of wire harness connector: (to Air Conditioning Amplifier Assembly)

    1. w/ Rear Heater


      1. Disconnect the A14 sensor connector.

      2. Disconnect the E35 amplifier connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        A14 (+) -1 - E35-10 (TAM) Always Below 1 Ω
        A14-2 (-) - E35-16 (SG-2)
        E35-10 (TAM) - Body ground Always 10 kΩ or higher
        E35-16 (SG-2) - Body ground

    2. w/o Rear Heater

      A01X2RTE01
      *a Front view of wire harness connector: (to Ambient Temperature Sensor)
      *b Rear view of wire harness connector: (to Air Conditioning Amplifier)

      1. Disconnect the A14 sensor connector.

      2. Disconnect the E81 amplifier connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        A14-1 (+) - E81-5 (TAM) Always Below 1 Ω
        A14-2 (-) - E81-13 (SG-2)
        E81-5 (TAM) - Body ground Always 10 kΩ or higher
        E81-13 (SG-2) - Body ground

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR