Inspection Procedure

WARNING: This page is about a different car, the 2004 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.

I 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.
  
  Fig 1: Inspecting Air Conditioning Amplifier (TAM, SG)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Voltage:
  
  at 25°C (77°F): 1.4-1.8 V
  
  at 40°C (104°F): 0.9-1.3V
HINT:

As the temperature increases, the voltage decreases.

NG: PROCEED TO NEXT CIRCUIT INSPECTION/SHOWN ON PROBLEM SYMPTOMS TABLE , refer to PROBLEM SYMPTOMS TABLE

OK: Go To Next Step.
INSPECT THERMISTOR ASSY
1. Remove the thermistor assy (ambient temp, sensor).
2. Measure resistance between terminal of the thermistor assy (ambient temp, sensor) connector at each temperature.
  
  Fig 2: Inspecting Thermistor Assy
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Resistance:
  
  at 25°C (77°F): 1.65-1.75 kΩ
  
  at 40°C (104°F): 0.85-0.95 kΩ
HINT:

As the temperature increases, the resistance decreases as shown in the illustration.

Fig 3: Thermistor Temperature Vs Resistance Graph
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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