Temperature sensor, external air (286): Connection

Fig 1: Circuit Diagram Temperature Sensor, External Air (286)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

One pin is grounded internally in the control module and the other supplied with 5V via a resistor of 6.8 kO built into the control module. The characteristics of the NTC resistor mean that the resistance falls as the temperature rises. This means that the voltage measured over the resistor will fall at the same time as the temperature rises. The power supply from the sensor is A/D-converted and then available in digital form. The digital voltage is then converted to temperature and stored in the control module working memory. A voltage value of almost 0 or 5V is interpreted as a fault in the circuit.