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 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 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 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 and 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 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

B005AB1E30
*a Thermistor Assembly (Ambient Temperature Sensor)
*b Air Conditioning Amplifier Assembly

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

  • The air conditioning system uses the CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the air conditioning system after confirming that the communication system is functioning properly.

    for LHD

    Click here

    for RHD

    Click here

PROCEDURE


  1. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    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

        • When short circuit: 65.95°C

      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

    INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY 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] - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the A16 thermistor assembly (ambient temperature sensor) connector.

    2. Disconnect the I50 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
      A16-2 - I50-5 (TAM) Always Below 1 Ω
      A16-1 - I50-13 (SG-2) Always Below 1 Ω
      A16-1 - A16-2 Always 10 kΩ or higher
      A16-2 or I50-5 (TAM) - Body ground Always 10 kΩ or higher
      A16-1 or I50-13 (SG-2) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR