AIR CONDITIONING SYSTEM, Diagnostic DTC:B1468

DTC Code DTC Name
B1468 Room Temperature Sensor Circuit (Rear Passenger Side)

DESCRIPTION

The No. 2 room temperature sensor detects the cabin temperature and controls the air conditioning system "AUTO" mode. The resistance of the No. 2 room temperature sensor changes according to changes in cabin temperature. The resistance value increases when the cabin temperature is low, and, conversely, decreases when the cabin temperature is high. The rear multiplex network door ECU sends the No. 2 room temperature sensor signal to the air conditioner amplifier assembly via CAN communication. The rear multiplex network ECU outputs voltage (5 V) to the No. 2 room temperature sensor, and reads changes in the voltage associated with changes in the resistance of the ambient temperature sensor.

The rear multiplex network door ECU sends the read signal to the air conditioning amplifier via the CAN communication line. The rear door ECU 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 multiplex network door ECU.

DTC No. Detection Item DTC Detection Condition Trouble Area Memory
B1468 Room Temperature Sensor Circuit (Rear Passenger Side)

  • Diagnosis condition: Ambient temperature is -30°C (-22 °F) or more

  • Malfunction status: Open or short in No. 2 room temperature sensor circuit

  • Detection time: None (Present malfunction), continuously for 4 seconds or more (Past malfunction)

  • Cooler thermistor (No. 2 room temperature sensor)

  • Harness or connector

  • Air conditioning amplifier assembly

  • Rear multiplex network door ECU RH (for LHD)

  • Rear multiplex network door ECU LH (for RHD)

 Memorized

WIRING DIAGRAM

Figure 1. for LHD:

B004TJ3E04

Figure 2. for RHD:

B004TJ3E05

CAUTION / NOTICE / HINT

Note

The air conditioning system uses the CAN communication system. First, confirm that there is no malfunction in the CAN communication system. Refer to the How to Proceed with Troubleshooting procedure.

Click here

PROCEDURE


  1. READ VALUE USING GTS (ROOM TEMPERATURE SENSOR)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.

    5. Read the Data List according to the display on the GTS.


      Body Electrical > Air Conditioner > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Room Temp Sensor (Rear) Cooler (rear room temp. sensor) thermistor

      Min.: -6.50°C (20.30°F)

      Max.: 57.25°C (135.05°F)

      		 Actual cabin temperature displayed

      Cooler thermistor system malfunction


      • When open circuit: -6.50°C (20.30°F)

      • When short circuit: 57.25°C (135.05°F)

      Body Electrical > Air Conditioner > Data List
      Tester Display
      Room Temp Sensor (Rear)
      OK
      The display is as specified in the normal condition column.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

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


    1. Remove the cooler thermistor (No. 2 room temperature sensor).

      Click here

    2. Inspect the cooler thermistor (No. 2 room temperature sensor).

      Click here

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  3. CHECK HARNESS AND CONNECTOR (REAR MULTIPLEX NETWORK DOOR ECU - COOLER THERMISTOR (NO. 2 ROOM TEMPERATURE SENSOR))


    1. for LHD:


      1. Disconnect the K7 rear multiplex network door ECU RH connector.

      2. Disconnect the J2 cooler thermistor (No. 2 room temperature sensor) connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        K7-20 (TRE) - J2-2 (SG) Always Below 1 Ω
        K7-21 (TRAD) - J2-1 (TRRR) Always Below 1 Ω
        K7-20 (TRE) or J2-2 (SG) - Other terminals and body ground Always 10 kΩ or higher
        K7-21 (TRAD) or J2-1 (TRRR) - Other terminals and body ground Always 10 kΩ or higher

    2. for RHD:


      1. Disconnect the K21 rear multiplex network door ECU LH connector.

      2. Disconnect the J6 cooler thermistor (No. 2 room temperature sensor) connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        K21-20 (TRE) - J6-2 (SG) Always Below 1 Ω
        K21-21 (TRAD) - J6-1 (TRRR) Always Below 1 Ω
        K21-20 (TRE) or J6-2 (SG) - Other terminals and body ground Always 10 kΩ or higher
        K21-21 (TRAD) or J6-1 (TRRR) - Other terminals and body ground Always 10 kΩ or higher

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

      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE REAR MULTIPLEX NETWORK DOOR ECU RH Click here

    B

    REPLACE REAR MULTIPLEX NETWORK DOOR ECU LH Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR