Cabin Temperature Sensor / Switch: Testing and Inspection

In-Car Temperature Sensor (Part 1 Of 2):

In-Car Temperature Sensor (Part 2 Of 2):

Self-diagnosis indicator light A comes on: A problem in the in-car temperature sensor circuit.

The in-car temperature sensor is a temperature dependent resistor (thermistor). The resistance of the thermistor decreases as the temperature inside the vehicle increases.




Compare the resistance reading between the No. 1 and No. 2 terminals of the in-car temperature sensor with the specifications shown in following graph; resistance should be within specifications.

NOTE: Check for change in resistance by heating or cooling the sensor with a hair drier, etc.

CAUTION: The sensor uses a thermistor which can be damaged if high current is applied during testing. Therefore, use a circuit tester with an output of 1 mAor less at the 20 K Ohms range.