Toyota RAV4 Service Manual: Ambient temperature sensor circuit
Description
The ambient temperature sensor is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner. The sensor is connected to the combination meter and detects fluctuations in the ambient temperature. This data is used for controlling the room temperature.
The sensor sends a signal to the air conditioning amplifier via the combination meter. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The air conditioning amplifier applies a voltage (5 v) to the ambient temperature sensor and reads voltage changes as changes in the resistance of the ambient temperature sensor. The combination meter sends the read signal to the air conditioning amplifier via can communication.
Wiring diagram
Inspection procedure
- Read value of intelligent tester (ambi temp sens)
- Connect the intelligent tester (with can vim) to the dlc3.
- Turn the ignition switch on and turn the intelligent tester main switch on.
- Select the item below in the data list, and read the value displayed on the intelligent tester.
Ok: the display is as specified in the normal condition column.
- Inspect ambient temperature sensor
- Remove the ambient temperature sensor.
- Measure the resistance of the sensor.
Standard resistance 
Notice:
- Touching the sensor even slightly may change the resistance value. Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
Hint:
As the temperature increases, the resistance decreases (see the graph).
- Check wire harness (ambient temperature sensor - combination meter)
- Disconnect the a17 sensor connector.
- Disconnect the e19 meter connector.
- Measure the resistance of the wire harness side connectors.
Standard resistance 
Replace combination meter
Diagnostic trouble code chart (2006/01- )
Hint:
When the air conditioning system functions properly, dtc
b1400/00 is output.
Hint:
*1: Dtc b1422/22 (compressor lock sensor circuit) is
indicated only for a currently occurring malfunct ...
Evaporator temperature sensor circuit
Description
The no. 1 Cooler thermistor (evaporator temperature sensor) is installed on
the evaporator in the air
conditioning unit to detect the temperature of the cooled air that has passed ...
Other materials:
Mil circuit
Description
The mil (malfunction indicator lamp) is used to indicate vehicle malfunction
detections by the ecm.
When the ignition switch is turned on, power is supplied to the mil circuit, and
the ecm provides the
circuit ground which illuminates the mil.
The mil operation can be checked ...
Bluetooth®
When using the bluetooth® audio system
In the following conditions, the system may not function.
If the portable audio player is turned off
If the portable audio player is not connected
If the portable audio player’s battery is low
There may be a delay if a cellular phone connection i ...
Catalyst system efficiency below threshold (bank 1)
Monitor description
The ecm uses sensors mounted in front of and behind the three-way catalytic
converter (twc) to
monitor its efficiency.
The first sensor, the air-fuel ratio (a/f) sensor, sends pre-catalyst
information to the ecm. The second
sensor, the heated oxygen (ho2) sensor, se ...