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.

INSPECT AIR CONDITIONING AMPLIFIER (TR, SG)
1. Remove the A/C amplifier with the connectors being connected.
2. Turn ignition switch to ON.
3. Measure voltage between terminal TR and SG of the A/C amplifier connector at each temperature.
  
  Fig 1: Inspecting Air Conditioning Amplifier (TR, SG)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Voltage:
  
  at 25°C (77°F): 1.8-2.2 V
  
  at 40°C (104°F): 1.2-1.6 V
HINT:

As the temperature increases, the voltage decreases.

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

NG: Go To Next Step.
INSPECT COOLER THERMISTOR
1. Remove the cooler thermistor (room temp, sensor).
2. Measure resistance between terminals of the cooler thermistor (Room temp, sensor) connector at each temperature.
  
  Fig 2: Inspecting Cooler Thermistor
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Resistance:
  
  at 25°C (77°F): 1.65-1.75 kΩ
  
  at 40°C (104°F): 0.55-0.65 kΩ
HINT:

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

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

NG: REPLACE COOLER THERMISTOR

OK: Go To Next Step.
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 ).
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 DTC 11 is not output again
  Standard: DTC 11 is not output.
OK: SYSTEM OK

NG: CHECK AND REPLACE AIR CONDITIONING AMPLIFIER