AIR CONDITIONING SYSTEM, Diagnostic DTC:B1412/12

DESCRIPTION

The ambient temperature sensor (thermistor assembly) is installed in front of the condenser. It detects the ambient temperature to control air conditioning AUTO mode. This sensor is connected to the air conditioning amplifier assembly and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the ambient temperature sensor (thermistor assembly) changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies voltage (5 V) to the ambient temperature sensor (thermistor assembly) and reads voltage changes as the resistance of the ambient temperature sensor (thermistor assembly) changes.

WIRING DIAGRAM

*a	Ambient Temperature Sensor (Thermistor Assembly)
*b	Air Conditioning Amplifier Assembly

CAUTION / NOTICE / HINT

PROCEDURE

1. READ VALUE USING GTS

   
   

   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. Check the value(s) by referring to the table below.

      Air Conditioner

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      Ambient Temp Sensor	Ambient temperature sensor (thermistor assembly) / Min: -23.30°C (-9.94°F) Max: 65.95°C (150.71°F)	Actual ambient temperature displayed	-

      OK
      The display is as specified in the Normal Condition column.

      Result
      Result Proceed to NG A OK (When troubleshooting according to Problem Symptoms Table) B OK (When troubleshooting according to the DTC) C

   
   

   B

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

   C

   REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

   A

2. INSPECT AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY)

   
   

   1. Remove the ambient temperature sensor (thermistor assembly) Click 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 1 - 2 15°C (59°F) 2.45 to 2.88 kΩ 1 - 2 20°C (68°F) 1.95 to 2.30 kΩ 1 - 2 25°C (77°F) 1.60 to 1.80 kΩ 1 - 2 30°C (86°F) 1.28 to 1.47 kΩ 1 - 2 35°C (95°F) 1.00 to 1.22 kΩ 1 - 2 40°C (104°F) 0.80 to 1.00 kΩ 1 - 2 45°C (113°F) 0.65 to 0.85 kΩ 1 - 2 50°C (122°F) 0.50 to 0.70 kΩ 1 - 2 55°C (131°F) 0.44 to 0.60 kΩ 1 - 2 60°C (140°F) 0.36 to 0.50 kΩ

      Note

      
      

      • Hold the sensor only by its connector. Touching the sensor may change the resistance value.

      • 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).

      Text in Illustration

      *a	Component without harness connected (Ambient Temperature Sensor (Thermistor Assembly))
      *b	Sensing Portion
      *c	Resistance (kΩ)
      *d	Allowable Range
      *e	Temperature (°C (°F))

   
   

   NG

   REPLACE AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY) Click here

   OK

3. CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY) - AIR CONDITIONING AMPLIFIER)

   
   

   1. Disconnect the L17 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition L17-5 (TAM) - A4-1 Always Below 1 Ω L17-13 (SG-2) - A4-2 Always Below 1 Ω L17-5 (TAM) - Body ground Always 10 kΩ or higher L17-13 (SG-2) - Body ground Always 10 kΩ or higher

   
   

   OK

   REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR