Toyota RAV4 (XA40) 2013-2018 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
Room temperature sensor circuit
Description
The room temperature sensor is installed in the instrument panel to detect
the room temperature and
control the heater and air conditioner auto mode. The resistance of the room
t ...
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:
For vehicles equipped with mobile communication systems
Install the antenna as far away from the ecu and
sensors of the vehicle electronic systems as
possible.
Install an antenna feeder at least 20 cm (7.87 In.)
Away from the ecu and sensors of the vehicle
electronic systems. For details about ecu and
sensor locations, refer to the sec ...
Open in occupant classification ecu battery positive line
Description
Dtc b1794 is set when a malfunction is detected in the occupant
classification ecu battery positive line.
Wiring diagram
Inspection procedure
Check for dtc
Turn the ignition switch on.
Clear the dtcs (see page rs-249).
Hint:
First clear dtcs stored in the ...
Air-fuel ratio (a/f) and heated oxygen (ho2) sensor
heater monitors (front a/f and rear ho2 sensor type)
Preconditions
The monitor will not run unless:
The mil is off.
Drive pattern
Connect the intelligent tester to the dlc3.
Turn the ignition switch on.
Turn the tester on.
Clear dtcs (if set) (see page es-35).
Start the engine.
Allow the engine to idle for 10 minute ...
