AIR CONDITIONING SYSTEM(for Automatic Air Conditioning System), Diagnostic DTC:B1419/19

DTC Code DTC Name
B1419/19 Rear Room Temperature Sensor Circuit

DESCRIPTION

The cooler thermistor (rear room temperature sensor) is installed in the rear panel. It detects the rear cabin temperature to control the air conditioning AUTO mode. The resistance of the cooler thermistor (rear room temperature sensor) changes in accordance with the rear cabin temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies a voltage (5 V) to the cooler thermistor (rear room temperature sensor) and reads voltage changes as the resistance of the cooler thermistor (rear room temperature sensor) changes.

DTC Code DTC Detection Condition Trouble Area
B1419/19 Open or short in the cooler thermistor (rear room temperature sensor) circuit.

  • Cooler thermistor (rear room temperature sensor)

  • Harness or connector

  • Air conditioning amplifier assembly

WIRING DIAGRAM

B001EZIE70
*a Cooler Thermistor (Rear Room Temperature Sensor)
*b Air Conditioning Amplifier Assembly

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (REAR ROOM TEMPERATURE SENSOR)


    1. Use the Data List to check if the rear room temperature sensor is functioning properly Click here.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Room Temp Sensor (Rear)

      Cooler thermistor (rear room temperature sensor) /

      Min.: -6.5°C (20.3°F)

      Max.: 57.25°C (135.05°F)

      		 Actual rear cabin temperature displayed

      Open in the circuit: -6.5°C (- 20.3°F).

      Short in the circuit: 57.25°C (135.05°F).
      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

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

  2. INSPECT COOLER THERMISTOR (REAR ROOM TEMPERATURE SENSOR)


    1. Remove the cooler thermistor (rear room temperature sensor) Click here.

      B001DYIE01
      Text in Illustration
      *a Resistance *b Allowable Range
      *c Temperature - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 - 2 10°C (50°F) 3.00 to 3.73 kΩ
      15°C (59°F) 2.45 to 2.88 kΩ
      20°C (68°F) 1.95 to 2.30 kΩ
      25°C (77°F) 1.60 to 1.80 kΩ
      30°C (86°F) 1.28 to 1.47 kΩ
      35°C (95°F) 1.00 to 1.22 kΩ
      40°C (104°F) 0.80 to 1.00 kΩ
      45°C (113°F) 0.65 to 0.85 kΩ
      50°C (122°F) 0.50 to 0.70 kΩ
      55°C (131°F) 0.44 to 0.60 kΩ
      60°C (140°F) 0.36 to 0.50 kΩ

      Note


      • Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.

      • When measuring, the sensor temperature must be the same as the ambient temperature.

      Tech Tips

      As the temperature increases, the resistance decreases (refer to the graph).


    NG

    REPLACE COOLER THERMISTOR (REAR ROOM TEMPERATURE SENSOR) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (REAR ROOM TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)


    1. Disconnect the G24 amplifier connector.

    2. Disconnect the Q19 sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Q19-1 - G24-17 (TR) Always Below 1 Ω
      Q19-2 - G24-7 (SG-6) Always Below 1 Ω
      Q19-1 - Body ground Always 10 kΩ or higher
      Q19-2 - Body ground Always 10 kΩ or higher

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR