Outside Temperature Sensor

Courtesy of VOLVO CARS CORPORATION

The function of the outside temperature sensor is to detect the vehicle's ambient temperature. The ambient temperature is required so that the engine control module (ECM) can regulate, among other things:

• the engine cooling fan (FC)
• the air conditioning (A/C) compressor's displacement.

The ambient temperature is also used as a substitute value in the event of a fault in certain components or functions and to control certain diagnostic functions.

The engine control module (ECM) supplies other control modules with the current outside temperature by transmitting information on the controller area network (CAN).

The temperature sensor is a resistor with a negative temperature coefficient, so called NTC type. It is supplied with power from the control module.

The resistance in the sensor changes according to the ambient temperature of the vehicle. This provides the engine control module (ECM) with a signal of between 0-5 V. Low temperature results in high resistance (high voltage). High temperature results in low resistance (low voltage).

The outside temperature sensor is positioned in the left door mirror.

The engine control module (ECM) can diagnose the outside temperature sensor. The sensor value can be read off using the diagnostic tool.