AIR CONDITIONING SYSTEM(for Manual Air Conditioning System), Diagnostic DTC:B1412

DTC Code DTC Name
B1412 Ambient Temperature Sensor Circuit

DESCRIPTION

The cooler (ambient temperature sensor) thermistor is installed in front of the cooler condenser assembly to detect the ambient temperature which is used to control the air conditioning system. 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 combination meter assembly. The resistance of the thermistor assembly 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 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.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B1412

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

  • CAN communication system

Memorized

(4 seconds or more)*

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

Tip:

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

WIRING DIAGRAM

E269965E01

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

      Thermistor assembly

      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 hereClick hereClick 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 (COMBINATION METER ASSEMBLY - COOLER [AMBIENT TEMPERATURE SENSOR] THERMISTOR)

    1. Disconnect the G16 combination meter assembly connector.

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

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      G16-35 (TX1+) - A26-2 (SO+)

      Always

      Below 1 Ω

      G16-34 (TX1-) - A26-1 (SO-)

      Always

      Below 1 Ω

      G16-35 (TX1+) - Body ground

      Always

      10 kΩ or higher

      G16-34 (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

      Tip:

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

    2. Check for DTCs.

      Body Electrical > Air Conditioner > Trouble Codes

      OK

      DTC B1412 is not output.

    Result

    Proceed to

    OK

    NG
    OK

    END (COMBINATION METER ASSEMBLY IS DEFECTIVE)

    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

    Click here