AIR CONDITIONING SYSTEM, Diagnostic DTC:B1412

DTC Code DTC Name
B1412 Ambient Temperature Sensor Circuit

DESCRIPTION

The cooler thermistor (ambient temperature sensor) is installed in the front part of the condenser assembly with receiver 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 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 combination meter assembly applies a voltage (5 V) to the cooler thermistor (ambient temperature sensor) and reads voltage changes as changes in the resistance of the cooler thermistor (ambient temperature sensor). The combination meter assembly sends the signal to the air conditioning amplifier assembly via CAN communication.

DTC Code DTC Detection Condition Trouble Area
B1412 An open or short in the cooler thermistor (ambient temperature sensor) circuit.

  • CAN communication system

  • Cooler thermistor (ambient temperature sensor)

  • Harness or connector

  • Combination meter assembly

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A003EQBE01

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK CAN COMMUNICATION SYSTEM


    1. Use the GTS to check if the CAN communication system is functioning normally Click here.

      Result
      Result Proceed to
      CAN DTC is not output A
      CAN DTC is output B

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    A

  2. READ VALUE USING GTS (AMBIENT TEMPERATURE SENSOR)


    1. Use the Data List to check if the cooler thermistor (ambient temperature sensor) is functioning properly Click here.

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

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

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    READ VALUE USING GTS (AMBIENT TEMPERATURE) Click here

    A

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

  3. READ VALUE USING GTS (AMBIENT TEMPERATURE)


    1. Use the Data List to check if the cooler thermistor (ambient temperature sensor) is functioning properly Click here.

      Combination Meter
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Ambient Temperature Outside temperature / Min.: -40°C (-40°F), Max.: 87.5°C (189.5°F) Almost the same as actual outside temperature -
      OK
      The display is as specified in the normal condition column.

    NG

    INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR) Click here

    OK

  4. CHECK COMBINATION METER ASSEMBLY


    1. Replace the combination meter assembly Click here.

    2. Clear the DTC Click here.

    3. Check for DTCs Click here.

      OK
      DTC B1412 is not output.

    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    OK

    END (COMBINATION METER ASSEMBLY IS DEFECTIVE)

  5. INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR)


    1. Remove the cooler thermistor (ambient temperature sensor).

    2. Inspect the cooler thermistor (ambient temperature sensor) Click here.


    NG

    REPLACE COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR)

    OK

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


    1. Disconnect the A14 cooler thermistor (ambient temperature sensor) connector.

    2. Disconnect the H20 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A14-1 - H20-37 (TX1-) Always Below 1 Ω
      A14-2 - H20-36 (TX1+)
      H20-37 (TX1-) - Body ground Always 10 kΩ or higher
      H20-36 (TX1+) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here