Inspection Procedure

WARNING: This page is about a different car, the 2006 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT AIR CONDITIONING AMPLIFIER (TAM, SG)
1. Remove the A/C amplifier with the connectors being connected.
2. Turn the ignition switch to ON.
3. Measure voltage between terminal TAM and SG of the A/C amplifier connector at each temperature.
  Voltage:
  
  at 25°C (77°F): 1.4 - 1.8 V
  
  at 40°C (104°F): 0.9 - 1.3 V
  
  HINT:
  
  As the temperature increases, the voltage decreases.
  
  Fig 1: Identifying A/C Amplifier Connector Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE

OK: GO TO NEXT STEP.

INSPECT THERMISTOR ASSY

Remove the thermistor assy (ambient temp. sensor).

Measure the resistance according to the value(s) in TERMINALS RESISTANCE SPECIFICATION .

Fig 2: Identifying Thermistor Assy Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard:

TERMINALS RESISTANCE SPECIFICATION

Tester connection	Condition	Specified condition
A1-1 - A1-2	10°C (50°F)	3.00 to 3.73 kΩ
A1-1 - A1-2	15°C (59°F)	2.45 to 2.88 kΩ
A1-1 - A1-2	20°C (68°F)	1.95 to 2.30 kΩ
A1-1 - A1-2	25°C (77°F)	1.60 to 1.80 kΩ
A1-1 - A1-2	30°C (86°F)	1.28 to 1.47 kΩ
A1-1 - A1-2	35°C (95°F)	1.00 to 1.22 kΩ
A1-1 - A1-2	40°C (104°F)	0.80 to 1.00 kΩ
A1-1 - A1-2	45°C (113°F)	0.65 to 0.85 kΩ
A1-1 - A1-2	50°C (122°F)	0.50 to 0.70 kΩ
A1-1 - A1-2	55°C (131°F)	0.44 to 0.60 kΩ
A1-1 - A1-2	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.
When measuring the sensor temperature, it must be the same as the ambient temperature.

HINT:

As the temperature increases, the resistance decreases (see the graph on Fig 3).

Fig 3: Thermistor Assy Terminals Resistance Graph

NG: REPLACE THERMISTOR ASSY

OK: GO TO NEXT STEP.

CHECK HARNESS AND CONNECTOR (BETWEEN THERMISTOR ASSY (AMBIENT TEMP. SENSOR) AND AIR CONDITIONING AMPLIFIER)
1. Check for open and short circuit in the harness and the connector between the thermistor assy (ambient temp. sensor) and the A/C amplifier (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step
CHECK DIAGNOSTIC TROUBLE CODE
1. Start up the DTC check mode.
2. Check that the DTC 12 is not output again.
  Standard: DTC 12 is not output.
OK: SYSTEM OK

NG: CHECK AND REPLACE AIR CONDITIONING AMPLIFIER