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 conditioner. 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).

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 between thermistor assembly (ambient temperature sensor) and air conditioning amplifier assembly

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A01UXUUE02
*a Thermistor Assembly (Ambient Temperature Sensor)
*b Air Conditioning Amplifier Assembly

PROCEDURE


  1. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON (IG).

    3. Turn the GTS on.

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

    5. According to the display on the GTS, 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

    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 B1412/12 is not output

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

  3. 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

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


    1. Disconnect the A17 thermistor assembly (ambient temperature sensor) connector.

    2. Disconnect the F29 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A17-1 (+) - F29-5 (TAM) Always Below 1 Ω
      A17-2 (-) - F29-13 (SG-2) Always Below 1 Ω
      A17-1 (+) - Body ground Always 10 kΩ or higher
      A17-2 (-) - Body ground Always 10 kΩ or higher

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR