Inspection Procedure

1. Remove the A/C amplifier with the connectors still connected.
2. Turn the ignition switch ON.
3. Measure the voltage between terminals TAM (A48-7) and FRSG (A48-18) of the A/C amplifier connector at each temperature.

   Standard voltage: 

   1.35 to 1.75 V at 25 °C (77°F) 

   0.85 to 1.25 V at 40 °C (104°F) 

   HINT:

   • As the temperature increases, the voltage decreases.
   • However, if DTC 12 is displayed, check and replace the A/C amplifier.
     Fig 1: Checking Air Conditioning Amplifier

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: REPLACE AIR CONDITIONING AMPLIFIER 

NG: Go to next step 

1. Disconnect the A1 ambient temperature sensor connector.
2. Measure the resistance between terminals 1 and 2 of the ambient temperature sensor connector at each temperature.

   Standard resistance: 

   1.6 to 1.8 kΩ at 25°C (77°F) 

   0.5 to 0.7 kΩ at 40 °C (104°F) 

   HINT:

   As the temperature increases, the resistance decreases.

   NOTE: When installing the ambient temperature sensor, be sure to connect the sensor connector before connecting the battery.

NG: REPLACE AMBIENT TEMPERATURE SENSOR 

Fig 2: Identifying A1 Ambient Temperature Sensor Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to next step 

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

OK: REPLACE AIR CONDITIONING AMPLIFIER