Inspection Procedure

WARNING: This page is about a different car, the 2005 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
  
  Fig 1: Inspecting Air Conditioning Amplifier (TAM, SG)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
HINT

As the temperature increases, the voltage decreases.
1. NG: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE
NG: Go to next step.

INSPECT THERMISTOR ASSY

Remove the thermistor assy (ambient temp, sensor).

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

Fig 2: Identifying Connector Terminal Thermistor Assy

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard:

RESISTANCE CONDITION

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 below).

NG: REPLACE COOLER THERMISTOR

NG: Go to next step.

Fig 3: Resistance Graph

CHECK HARNESS AND CONNECTOR (BETWEEN COOLER THERMISTOR (ROOM TEMP. SENSOR) AND AIR CONDITIONING AMPLIFIER)
1. Check for open and short circuit in the harness and the connector between the cooler thermistor (room temp, sensor) and the A/C amplifier (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).
1. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
NG: Go to next step.
CHECK DIAGNOSTIC TROUBLE CODE
1. Start up the DTC check mode.
2. Check that DTC 12 is not output again.
  Standard: DTC 12 is not output.
1. OK: SYSTEM OK
NG: Go to next step.

CHECK AND REPLACE AIR CONDITIONING AMPLIFIER