AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System), Diagnostic DTC:21

DTC Code DTC Name
21 Solar Sensor Circuit

DESCRIPTION

A01DZVBE01

The cooler thermistor (solar sensor), which is installed on the upper side of the instrument panel, detects sunlight and controls the air conditioning in AUTO mode. The output current from the cooler thermistor (solar sensor) varies according to the amount of sunlight. When the amount of sunlight increases, the output current increases. As the amount of sunlight decreases, the output current decreases. The air conditioning amplifier assembly detects the output current from the cooler thermistor (solar sensor).

DTC Code Detection Item Trouble Area
21

An open in cooler thermistor (solar sensor) circuit

(If check is performed in a dark place, DTC 21 may be stored)

  • Cooler thermistor (solar sensor)

  • Harness or connector

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A01DZ53E03

INSPECTION PROCEDURE

Tech Tips

If the check is performed in a dark place, DTC 21 may be stored even though the system is normal.

PROCEDURE


  1. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY


    1. A01DVCGE10
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Remove the air conditioning amplifier assembly with its connectors still connected Click here.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A46-2 (S5-3) - A46-7 (TS)

      • Ignition switch ON

      • Solar sensor subjected to electric light

      • Vehicle indoors

      		 0.8 to 4.3 V

      • Ignition switch ON

      • Solar sensor covered with a cloth

      • Vehicle indoors

      		 Below 0.8 V

      Tech Tips


      • As the inspection light is moved away from the sensor, the voltage decreases.

      • Use an incandescent light for inspection. Bring it within 30 cm (11.8 in.) of the sensor.

      Result
      Result Proceed to
      OK (When troubleshooting according to problem symptoms table.) A
      OK (When troubleshooting according to DTC.) B
      NG C

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    INSPECT COOLER THERMISTOR (SOLAR SENSOR) Click here

    A

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

  2. INSPECT COOLER THERMISTOR (SOLAR SENSOR)


    1. A01E1SI

      Remove the cooler thermistor (solar sensor) Click here.

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


      1. Connect the positive (+) lead of the ohmmeter to terminal 2 and the negative (-) lead to terminal 1 of the cooler thermistor.

        Standard Resistance
        Tester Connection Condition Specified Condition
        1 - 2

        • Vehicle indoors

        • Solar sensor is subjected to electric light

        		 Below 10 kΩ

        • Vehicle indoors

        • Solar sensor is covered with a cloth

        		 10 kΩ or higher

        Note

        The connection procedure for a digital tester, such as a TOYOTA electrical tester, is shown above. When using an analog tester, connect the negative (-) lead to terminal 2 and positive (+) lead to terminal 1.

        Tech Tips


        • As the inspection light is moved away from the cooler thermistor (solar sensor), the resistance increases.

        • Use an incandescent light for inspection. Bring it within 30 cm (11.8 in.) from the sensor.


    NG

    REPLACE COOLER THERMISTOR (SOLAR SENSOR) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (SOLAR SENSOR - AIR CONDITIONING AMPLIFIER)


    1. Disconnect the A35 cooler thermistor (solar sensor) connector.

    2. Disconnect the A46 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A46-2 (S5-3) - A35-1 Always Below 1 Ω
      A46-7 (TS) - A35-2
      A46-2 (S5-3) - Body ground Always 10 kΩ or higher
      A46-7 (TS) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here