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 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 Condition Trouble Area
B1412/12 Open or short in ambient temperature sensor circuit

  • Ambient temperature sensor

  • Wire harness between ambient temperature sensor and Air conditioning amplifier

  • Air conditioning amplifier

WIRING DIAGRAM

A017CJEE04

INSPECTION PROCEDURE

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (AMBI TEMP SENS)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the intelligent teste main switch on.

    3. Select the item below in the Data List, and read the value displayed on the intelligent teste.

      Data List / Air Conditioner:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Ambi Temp Sens

      Ambient temperature sensor /

      Min.: -23.3°C (-9.94°F)

      Max.: 65.94°C (150.71°F)

      		 Actual ambient temperature is displayed

      Open circuit: -23.3°C (-9.94°F)

      Short circuit: 65.94°C (150.71°F)
      OK
      The display is as specified in the normal condition column.
      Result
      Result Proceed to
      NG A
      OK (Checking from PROBLEM SYMPTOMS TABLE) B
      OK (Checking from DTC) C

    B

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    REPLACE AIR CONDITIONING AMPLIFIER Click here

    A

  2. INSPECT AMBIENT TEMPERATURE SENSOR


    1. A017FDXE16

      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
      A7-1 - A7-2 10°C (50°F) 3.00 to 3.73 kΩ
      A7-1 - A7-2 15°C (50°F) 2.45 to 2.88 kΩ
      A7-1 - A7-2 20°C (68°F) 1.95 to 2.30 kΩ
      A7-1 - A7-2 25°C (77°F) 1.60 to 1.80 kΩ
      A7-1 - A7-2 30°C (86°F) 1.28 to 1.47 kΩ
      A7-1 - A7-2 35°C (95°F) 1.00 to 1.22 kΩ
      A7-1 - A7-2 40°C (104°F) 0.80 to 1.00 kΩ
      A7-1 - A7-2 45°C (113°F) 0.65 to 0.85 kΩ
      A7-1 - A7-2 50°C (122°F) 0.50 to 0.70 kΩ
      A7-1 - A7-2 55°C (131°F) 0.44 to 0.60 kΩ
      A7-1 - A7-2 60°C (140°F) 0.36 to 0.50 kΩ

      Note


      • Touching the sensor even slightly 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)


    1. A017BTLE03

      Disconnect the A7 sensor connector.

    2. Disconnect the D33 amplifier connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A7-1 - D33-5 (TAM) Always Below 1 Ω
      A7-2 - D33-13 (SG-2) Always Below 1 Ω
      D33-5 (TAM) - Body ground Always 10 kΩ or higher
      D33-13 (SG-2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here