Inspection Procedure

1. Connect Techstream to the DLC3.
2. Turn the ignition switch ON and turn Techstream ON.
3. Select the item below in the Data List, and read the value displayed on Techstream.

   Air conditioning amplifier 

   DATA LIST - AIR CONDITIONING AMPLIFIER
   
   

   Item	Measurement Item / Display (Range)	Normal Condition	Diagnostic Note
   Room Temperature Sensor	Room temperature sensor / Min.: -6.5°C (20.3°F) Max.: 57.25°C (135.05°F)	Actual room temperature is displayed	Open circuit: -6.5°C (20.3°F) Short circuit: 57.25X (135.05°F)

   OK: 

   The display is as specified in the normal condition column. 

   Result 

   RESULT REFERENCE
   
   

   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 

C: REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 

A: Go to next step 

1. Remove the room temperature sensor.
   Fig 1: Identifying Room Temperature Sensor Resistance Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance of the sensor.

   Standard resistance 

   RESISTANCE SPECIFICATION
   
   

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

   HINT:

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

NG: REPLACE COOLER THERMISTOR (ROOM TEMPERATURE SENSOR) 

OK: Go to next step 

1. Disconnect the E21 sensor connector.
2. Disconnect the E37 amplifier connector.
   Fig 2: Identifying E21 And E37 Amplifier Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   RESISTANCE SPECIFICATION
   
   

   Tester Connection	Specified Condition
   E21-1 (ST+) - E37-29 (TR)	Below 1 Ω
   E21-2 (ST-) - E37-34 (SG-1)	Below 1 Ω
   E21-1 (ST+) - Body ground	1 MΩ or higher
   E21-2 (ST-) - Body ground	1 MΩ or higher

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

OK: REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY