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)

-
Tip:

  • 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

E316651E07

CAUTION / NOTICE / HINT

Note:

  • 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.

    Click here

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

    Click here

PROCEDURE

  1. READ VALUE USING GTS (AMBIENT TEMP SENSOR)

    1. Connect the GTS to the DLC3.

    2. Turn the power 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 (-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 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 A26 thermistor assembly (ambient temperature sensor) 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

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

      Always

      Below 1 Ω

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

      Always

      Below 1 Ω

      A26-2 (SO+) - A26-1 (SO-)

      Always

      10 kΩ or higher

      A26-2 (SO+) or G16-35 (TX1+) - Body ground

      Always

      10 kΩ or higher

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