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

DTC Code DTC Name
B1412/12 Ambient Temperature Sensor Circuit

DESCRIPTION

The cooler (ambient temperature sensor) thermistor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioning system AUTO mode. This sensor is connected to the air conditioning amplifier assembly and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the cooler (ambient temperature sensor) thermistor changes in accordance with the 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 cooler (ambient temperature sensor) thermistor and reads voltage changes due to changes in the resistance of the cooler (ambient temperature sensor) thermistor. The combination meter assembly sends the read signal to the air conditioning amplifier via CAN communication.

DTC No. Detection Item DTC Detection Condition Trouble Area Memory Note
B1412/12 Ambient Temperature Sensor Circuit Open or short in cooler (ambient temperature sensor) thermistor circuit

  • Cooler (ambient temperature sensor) thermistor

  • Harness or connector

  • Air conditioning amplifier assembly

  • Combination meter assembly

 Memorized (4 seconds or more) -

Tech Tips


  • The air conditioning amplifier assembly stores the DTC of the respective malfunction if it has occurred for the period of time indicated in the brackets.

  • If the ambient temperature is approximately -52.9°C (-63.22°F) or less, DTC B1412/12 may be output even though the system is normal.

WIRING DIAGRAM

A01V964E01
*a Cooler (Ambient Temperature Sensor) Thermistor
*b Combination Meter Assembly
*c Air Conditioning Amplifier Assembly
*d CAN Communication Line

CAUTION / NOTICE / HINT

Note

When the battery is disconnected or the air conditioning amplifier assembly is replaced, be sure to perform servo motor initialization.

Click here

PROCEDURE


  1. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

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

    5. Check the value(s) by referring to the table below.


      Body Electrical > Air Conditioner > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Ambient Temp Sensor Cooler (ambient temperature sensor) thermistor

      Min.: -23.30°C (-9.94°F)

      Max.: 65.95°C (150.71°F)

      		 Actual ambient temperature displayed -

      Body Electrical > Air Conditioner > Data List
      Tester Display
      Ambient Temp Sensor
      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

    A

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

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

  2. INSPECT COOLER (AMBIENT TEMPERATURE SENSOR) THERMISTOR


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

      Click here

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE COOLER (AMBIENT TEMPERATURE SENSOR) THERMISTOR Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (COOLER [AMBIENT TEMPERATURE SENSOR] THERMISTOR - COMBINATION METER ASSEMBLY)


    1. Disconnect the A26 cooler (ambient temperature sensor) thermistor connector.

    2. Disconnect the G16 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A26-1 (SO-) - G16-34 (TX1-) Always Below 1 Ω
      A26-2 (SO+) - G16-35 (TX1+) Always Below 1 Ω
      A26-1 (SO-) - Body ground Always 10 kΩ or higher
      A26-2 (SO+) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR