AIR CONDITIONING SYSTEM(for Manual Cooler 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 front of the cooler condenser assembly to detect the ambient temperature which is used to control the air conditioning system AUTO mode. This sensor is connected to the combination meter 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 via the combination meter assembly. The resistance of the thermistor assembly (ambient temperature sensor) changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. Conversely, 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 due to changes in the resistance of the thermistor assembly (ambient temperature sensor).

DTC No. Detection Item DTC Detection Condition Trouble Area Memory Note
B1412/12 Ambient Temperature Sensor Circuit

  • Diagnosis condition: None

  • Malfunction state: Open or short in thermistor assembly (ambient temperature sensor) circuit

  • Malfunction Period: None (as present malfunction), memorized (4 seconds or more) (as past malfunction)

  • Thermistor assembly (ambient temperature sensor)

  • Harness or connector

  • Air conditioning amplifier 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 parentheses.

  • 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

B003NG1E10
*a Thermistor Assembly (Ambient Temperature Sensor)
*b Combination Meter Assembly
*c Air Conditioning Amplifier Assembly
*d CAN Communication Line

PROCEDURE


  1. READ VALUE USING GTS (AMBIENT TEMP SENSOR)


    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 Thermistor assembly (ambient temperature sensor)

      Min.: -23.30°C (-9.94°F)

      Max.: 65.95°C (150.71°F)

      		 Actual ambient temperature displayed

      Thermistor assembly (ambient temperature sensor) system malfunction:


      • When open circuit: -23.30°C (-9.94°F)

      • When short circuit: 65.95°C (150.71°F)

      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 the DTC) A
      OK (When troubleshooting according to Problem Symptoms Table) B
      NG C

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

    B

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

    C

  2. 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
      Proceed to
      OK
      NG

    NG

    REPLACE THERMISTOR ASSEMBLY (AMBIENT TEMPERATURE SENSOR) Click here

    OK

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


    1. Disconnect the A32 thermistor assembly (ambient temperature sensor) connector.

    2. Disconnect the G8 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A32-2 (+) - G8-33 (TX1+) Always Below 1 Ω
      A32-1 (-) - G8-34 (TX1-) Always Below 1 Ω
      A32-1 (-) - A32-2 (+) Always 10 kΩ or higher
      A32-2 (+) or G8-33 (TX1+) - Body ground Always 10 kΩ or higher
      A32-1 (-) or G8-34 (TX1-) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK COMBINATION METER ASSEMBLY


    1. Replace the combination meter assembly.

      Click here

      Tech Tips

      Since the combination meter assembly cannot be inspected while it is removed from the vehicle, replace the combination meter assembly with a normal one and check that the condition returns to normal.

    2. Clear the DTC using the GTS or performing the panel diagnosis (sensor check).

      Click here


      Body Electrical > Air Conditioner > Clear DTCs

    3. Check for DTCs when the following conditions are met using the GTS or performing the panel diagnosis (sensor check).

      Click here


      Body Electrical > Air Conditioner > Trouble Codes
      OK
      DTC B1412/12 is not output.
      Result
      Proceed to
      OK
      NG

    OK

    END (COMBINATION METER ASSEMBLY IS NOT NORMAL)

    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here