AIR CONDITIONING SYSTEM(for Manual Air Conditioning System), Diagnostic DTC:B1412

DTC Code DTC Name
B1412 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 conditioner. The sensor connected to the combination meter assembly detects fluctuations in the ambient temperature. This data is used for controlling the room temperature. The sensor sends a signal to the combination meter 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 combination meter 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.

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

  • Thermistor assembly (ambient temperature sensor)

  • Harness or connector

  • Air conditioning amplifier assembly

  • Combination meter assembly

  • CAN communication system

WIRING DIAGRAM

A01VDL3E03
*a Thermistor Assembly (Ambient Temperature Sensor)
*b Air Conditioning Amplifier Assembly
*c Combination Meter Assembly
*d CAN Communication Line

PROCEDURE


  1. CHECK FOR DTC (CAN COMMUNICATION SYSTEM)


    1. Use the intelligent tester to check if the CAN communication system is functioning normally.

      OK
      CAN DTC is not output

    NG

    GO TO CAN COMMUNICATION SYSTEM Click here

    OK

  2. READ VALUE USING INTELLIGENT TESTER


    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 / Combination Meter / Data List.

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

      Combination Meter
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Ambient Temperature

      Ambient temperature sensor /

      Min.: -40°C (-40°F)

      Max.: 87.5°C (189.5°F)

      		 Actual ambient temperature is displayed -
      OK
      The display is as specified in the normal condition column.

    NG

    INSPECT THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR) Click here

    OK

  3. READ VALUE USING INTELLIGENT TESTER


    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

      Ambient temperature sensor /

      Min.: -23.3°C (-9.94°F)

      Max.: 65.95°C (150.71°F)

      		 Actual ambient temperature is displayed -
      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

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    A

  4. CHECK FOR DTC


    1. Clear the DTCs Click here.

    2. Check for DTCs Click here.

      OK
      DTC B1412 is not output

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

  5. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY


    1. Temporarily replace the air conditioning amplifier assembly with a new or normally functioning one Click here.


    NEXT

  6. CHECK FOR DTC


    1. Clear the DTCs Click here.

    2. Check for DTCs Click here.

      OK
      DTC B1412 is not output

    OK

    END (AIR CONDITIONING AMPLIFIER ASSEMBLY IS FAULTY)

    NG

    REPLACE COMBINATION METER ASSEMBLY Click here

  7. INSPECT THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR)


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


    NG

    REPLACE THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR) Click here

    OK

  8. CHECK HARNESS AND CONNECTOR (THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR) - AIR CONDITIONING AMPLIFIER 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
      Tester Connection Condition Specified Condition
      A24-2 - F1-35 (TX1+) Always Below 1 Ω
      A24-1 - F1-34 (TX1-) Always Below 1 Ω
      A24-2 - Body ground Always 10 kΩ or higher
      A24-1 - Body ground Always 10 kΩ or higher

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR