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 rear room temperature sensor is installed in the rear panel to detect the rear room temperature and control the heater and air conditioning AUTO mode. The resistance of the rear room temperature sensor changes in accordance with the rear room temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

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

DTC No. DTC Detection Condition Trouble Area
B1419/19 Open or short in rear room temperature sensor circuit

  • Rear room temperature sensor

  • Wire harness between rear room temperature sensor and air conditioning amplifier

  • Air conditioning amplifier

WIRING DIAGRAM

A017CR4E11

INSPECTION PROCEDURE

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (REAR ROOM TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the intelligent tester main switch on.

    3. Select the item below in the Data List, and read the value displayed on the intelligent tester.

      Data List / Air Conditioner:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Rear room Temp

      Rear room temperature sensor /

      Min.: -6.5°C (20.3°F)

      Max.: 57.25°C (135.05°F)

      		 Actual rear room temperature is displayed

      Open circuit: -6.5°C (20.3°F)

      Short circuit: 57.25°C (135.05°F)
      OK
      The display is as specified in the normal condition column.
      Result
      Result Proceed to
      NG A
      OK (Checking from the PROBLEM SYMPTOMS TABLE) B
      OK (Checking from the DTC) C

    B

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    REPLACE AIR CONDITIONING AMPLIFIER Click here

    A

  2. INSPECT REAR ROOM TEMPERATURE SENSOR


    1. A017FWOE02

      Remove the rear room temperature sensor Click here.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      N12-1 (+) - N12-2 (-) 10°C (50°F) 3.00 to 3.73 kΩ
      N12-1 (+) - N12-2 (-) 15°C (59°F) 2.45 to 2.88 kΩ
      N12-1 (+) - N12-2 (-) 20°C (68°F) 1.95 to 2.30 kΩ
      N12-1 (+) - N12-2 (-) 25°C (77°F) 1.60 to 1.80 kΩ
      N12-1 (+) - N12-2 (-) 30°C (86°F) 1.28 to 1.47 kΩ
      N12-1 (+) - N12-2 (-) 35°C (95°F) 1.00 to 1.22 kΩ
      N12-1 (+) - N12-2 (-) 40°C (104°F) 0.80 to 1.00 kΩ
      N12-1 (+) - N12-2 (-) 45°C (113°F) 0.65 to 0.85 kΩ
      N12-1 (+) - N12-2 (-) 50°C (122°F) 0.50 to 0.70 kΩ
      N12-1 (+) - N12-2 (-) 55°C (131°F) 0.44 to 0.60 kΩ
      N12-1 (+) - N12-2 (-) 60°C (140°F) 0.36 to 0.50 kΩ

      Note


      • Touching the sensor even slightly 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 (see the graph).


    NG

    REPLACE REAR ROOM TEMPERATURE SENSOR Click here

    OK

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


    1. A017D8UE03

      Disconnect the N12 sensor connector.

    2. Disconnect the D34 amplifier connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      N12-1 - D34-17 (TR) Always Below 1 Ω
      N12-2 - D34-7 (SG-6) Always Below 1 Ω
      N12-1 - Body ground Always 1 MΩ or higher
      N12-2 - Body ground Always 1 MΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here