Toyota RAV4 Service Manual: 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 temperature sensor changes in accordance with the room 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 room temperature sensor and reads voltage changes as changes in the resistance of the room temperature sensor.
Wiring diagram
Inspection procedure
- Read value of intelligent tester (room temp)
- 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 cooler thermistor (room temperature sensor)
- Remove the room 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 (room temperature sensor - air conditioning amplifier)
- Disconnect the e21 sensor connector.
- Disconnect the e37 amplifier connector.
- Measure the resistance of the wire harness side connectors.
Standard resistance 
Replace air conditioning amplifier assembly
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 malf ...
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
c ...
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 ...
Gauges and meters
The units used on the speedometer may differ depending on the target
region.
Tachometer
Displays the engine speed in revolutions per minute
Speedometer
Displays the vehicle speed
Fuel gauge
Displays the quantity of fuel remaining in the tank
Shift position and shift ran ...
Throttle / pedal position sensor / switch "A" circuit range / performance
problem
Hint:
This dtc relates to the throttle position (tp) sensor.
Description
Refer to dtc p0120 (see page es-114).
Monitor description
The ecm uses the tp sensor to monitor the throttle valve opening angle.
This sensor transmits two signals: vta1 and vta2. Vta1 is used to detect the
th ...