AIR CONDITIONING SYSTEM, Diagnostic DTC:B1412/12

DTC Code DTC Name
B1412/12 Ambient Temperature Sensor Circuit

DESCRIPTION

The thermistor assembly 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 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 and reads voltage changes due to changes in the resistance of the thermistor assembly.

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

Any of the following conditions is met:


  • Open in thermistor assembly circuit

  • Short in thermistor assembly circuit

  • Thermistor assembly

  • 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.

DTC Detection Conditions
Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition Power switch on (IG) ○ ○
Malfunction Status Open in thermistor assembly circuit ○ -
Short in thermistor assembly circuit - ○
Detection Time 4 seconds or more 4 seconds or more
Number of Trips 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

A01MHHHE01
*a Thermistor Assembly
*b Air Conditioning Amplifier Assembly

PROCEDURE


  1. READ VALUE USING GTS


    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

      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

    INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

  2. INSPECT THERMISTOR ASSEMBLY


    1. Remove the thermistor assembly.

      Click here

    2. Inspect the thermistor assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE THERMISTOR ASSEMBLY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (THERMISTOR ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the A4 thermistor assembly connector.

    2. Disconnect the G43 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
      A4-1 - G43-5 (TAM) Always Below 1 Ω
      A4-2 - G43-13 (SG-2) Always Below 1 Ω
      A4-1 - A4-2 Always 10 kΩ or higher
      A4-1 or G43-5 (TAM) - Body ground Always 10 kΩ or higher
      A4-2 or G43-13 (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