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

DTC Code DTC Name
B1412/12 Ambient Temperature Sensor Circuit

DESCRIPTION

The thermistor assembly (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 thermistor assembly (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 thermistor assembly (ambient temperature sensor) and reads voltage changes as changes in the resistance of the thermistor assembly (ambient temperature sensor).

The combination meter assembly sends these signals to the air conditioning amplifier assembly.*1

DTC No. DTC Detection Condition Trouble Area
B1412/12 An open or short in the thermistor assembly (ambient temperature sensor) circuit.

  • Thermistor assembly (ambient temperature sensor)

  • Harness or connector

  • Combination meter assembly*1

  • Air conditioning amplifier assembly*2

*1 : w/ Rear Fog Light

*2 : w/o Rear Fog Light

WIRING DIAGRAM

A005GIPE04
w/ Rear Fog Light
*a THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR)
*b COMBINATION METER ASSEMBLY
*c AIR CONDITIONING AMPLIFIER ASSEMBLY
*d CAN Communication Line
A005KE8E28
w/o Rear Fog Light
*a THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR)
*b AIR CONDITIONING AMPLIFIER ASSEMBLY

PROCEDURE


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


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the intelligent tester on.

    4. Enter the following menus: Body / Air Conditioner / Data List.

    5. According to the display on the intelligent tester, read the Data List.

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

      Thermistor assembly (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 the DTC) A
      OK (When troubleshooting according to problem symptoms table) B
      NG C

    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    INSPECT THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR) Click here

    A

  2. CHECK FOR DTC


    1. Clear the DTCs Click here.

    2. Check for DTCs Click here.

      OK
      DTC B1412 is not output
      Result
      Result Proceed to
      OK A
      NG (w/ Rear Fog Light) B
      NG (w/o Rear Fog Light) C

    A

    END

    B

    REPLACE COMBINATION METER ASSEMBLY Click here

    C

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

  3. INSPECT THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR)


    1. Remove the thermistor assembly (ambient temperature sensor Click here.

    2. Inspect the thermistor assembly (ambient temperature sensor Click here.

      Result
      Result Proceed to
      OK (w/o Rear Fog Light) A
      OK (w/ Rear Fog Light) B
      NG C

    B

    CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - COMBINATION METER ASSEMBLY) Click here

    C

    REPLACE THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR) Click here

    A

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


    1. Disconnect the A24 thermistor assembly (ambient temperature sensor) connector.

    2. Disconnect the F42 air conditioning amplifier assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A24-2 - F42-5 (TAM) Always Below 1 Ω
      A24-1 - F42-13 (SG-2) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A24-1 - Body ground Always 10 kΩ or higher
      A24-2 - Body ground Always 10 kΩ or higher

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  5. CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - COMBINATION METER ASSEMBLY)


    1. Disconnect the A24 thermistor assembly (ambient temperature sensor) connector.

    2. Disconnect the F1 combination meter assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A24-2 - F1-35 (TX1+) Always Below 1 Ω
      A24-1 - F1-34 (TX1-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A24-1 - Body ground Always 10 kΩ or higher
      A24-2 - Body ground Always 10 kΩ or higher

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR