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 No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

Note

B1419/19

Rear Room Temperature Sensor Circuit

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

Stored

(4 seconds or more)

-

WIRING DIAGRAM

E156584E75

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

      Body Electrical > Air Conditioner > Data List

      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

      E252328C01

      *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.

      Tip:

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

    Result

    Result

    OK

    NG
    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 G12 amplifier connector.

    2. Disconnect the Q21 sensor connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      Q21-1 - G12-17 (TR)

      Always

      Below 1 Ω

      Q21-2 - G12-7 (SG-6)

      Always

      Below 1 Ω

      Q21-1 - Body ground

      Always

      10 kΩ or higher

      Q21-2 - Body ground

      Always

      10 kΩ or higher

    Result

    Result

    OK

    NG
    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR