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 (No. 2 room temp. sensor) thermistor is installed in the rear panel to detect the rear cabin temperature, which is used to control the air conditioning system. The resistance of the cooler (No. 2 room temp. sensor) thermistor 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 voltage (5 V) to the cooler (No. 2 room temp. sensor) thermistor and reads voltage changes due to changes in the resistance of the cooler (No. 2 room temp. sensor) thermistor.

DTC No. Detection Item DTC Detection Condition Trouble Area Memory
B1419/19 Rear Room Temperature Sensor Circuit Open or short in rear room temperature sensor circuit

  • Cooler (No. 2 room temp. sensor) thermistor

  • Harness or connector between cooler (No. 2 room temp. sensor) thermistor and air conditioning amplifier assembly

  • Air conditioning amplifier assembly

Memorized

(4 sec. or more)*1

WIRING DIAGRAM

A0028HHE60
*a Cooler (No. 2 Room Temp. Sensor) Thermistor
*b Air Conditioning Amplifier Assembly

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
      Room Temp Sensor (Rear) Cooler (No. 2 room temp. sensor) thermistor

      Min.: -6.50°C (20.30°F)

      Max.: 57.25°C (135.05°F)

      		 Actual rear cabin temperature displayed -

      Body Electrical > Air Conditioner > Data List
      Tester Display
      Room Temp Sensor (Rear)
      OK
      The display is as specified in the normal condition column.
      Result
      Result Proceed to
      NG A
      OK (When troubleshooting according to Problem Symptoms Table) B
      OK (When troubleshooting according to the DTC) C

    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    A

  2. INSPECT COOLER (NO. 2 ROOM TEMP. SENSOR) THERMISTOR


    1. A002753C01
      *a

      Component without harness connected

      (Cooler (No. 2 Room Temp. Sensor) Thermistor)
      *b Resistance (kΩ)
      *c Temperature (°C (°F))
      *d Allowable Range

      Remove the cooler (No. 2 room temp. sensor) thermistor.

      Click here

    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

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

      Tech Tips

      As the temperature increases, the resistance decreases (see the graph).

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE COOLER (NO. 2 ROOM TEMP. SENSOR) THERMISTOR Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (COOLER (NO. 2 ROOM TEMP. SENSOR) THERMISTOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the F81 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F81-20 (TR) - L17-1 Always Below 1 Ω
      F81-8 (RGND) - L17-2 Always Below 1 Ω
      F81-20 (TR) - Body ground Always 10 kΩ or higher
      F81-8 (RGND) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR