Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 2500 HD and 2012 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The Coolant Temperature Sensor is a variable resistor that functions as a normal two wire 5 volt sensor. The PCM supplies a 5 volt reference on the signal circuit, and a ground to the sensors low reference signal circuit.