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AIR CONDITIONING SYSTEM, Diagnostic DTC:B1419/19

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

The rear room temperature sensor LH is installed in the rear door trim board LH to detect the rear room temperature and control the heater and air conditioner "AUTO" mode. The resistance of the rear room temperature sensor changes in accordance with the rear room temperature for LH seat. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The rear door ECU LH sends the read signal to the air conditioning amplifier via the CAN communication line. The rear door ECU LH applies voltage (5 V) to the rear room temperature sensor and reads voltage changes as the resistance of the rear room temperature sensor changes. This sensor also sends the appropriate signals to the rear door ECU LH.

Tip:

This circuit uses the CAN communication line. Before performing the inspection, check that the CAN communication system is functioning normally.

DTC Code DTC Detection Condition Trouble Area
B1419/19 Open or short in rear room temperature sensor LH circuit

  • Rear room temperature sensor LH

  • Harness or connector between rear room temperature sensor LH and rear door ECU LH

  • Rear door ECU LH

  • Air conditioning amplifier

  • CAN communication line
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WIRING DIAGRAM

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INSPECTION PROCEDURE

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PROCEDURE


  1. Click here

    READ VALUE USING INTELLIGENT TESTER (REAR ROOM TEMPERATURE SENSOR)


    1. Use the Data List to check if the rear room temperature sensor for LH seat is functioning properly.

      Table 1. Air Conditioner
      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Room Temperature Sensor (Rear)

      Rear room temperature sensor for LH seat/

      Min.: -6.5°C (20.3°F)

      Max.: 57.25°C (135.05°F)

      		 Actual rear room temperature for LH seat is displayed

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

      Short in circuit: 57.25°C (135.05°F)
      OK
      The display is as specified in the normal condition.

  2. Click here

    INSPECT REAR ROOM TEMPERATURE SENSOR LH


    1. Remove the rear room temperature sensor LH (see pageClick 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:

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

      Tip:

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


  3. Click here

    CHECK HARNESS AND CONNECTOR (REAR ROOM TEMPERATURE SENSOR LH - REAR DOOR ECU LH)


    1. Disconnect the Q9 rear room temperature sensor LH connector.

    2. Disconnect the O15 rear door ECU LH connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      Q9-2 - O15-26 (TRE) Always Below 1 Ω
      Q9-1 - O15-13 (TRAD)
      O15-26 (TRE) - Body ground Always 10 kΩ or higher
      O15-13 (TRAD) - Body ground

  4. Click here

    REPLACE REAR DOOR ECU LHClick here

  5. Click here

    REPLACE AIR CONDITIONING AMPLIFIERClick here

  6. Click here

    REPLACE REAR ROOM TEMPERATURE SENSOR LHClick here

  7. Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR