Just a quick question, why does a coolant temperature sensor have a second resistor within the Engine ECU which isn't a variable resistor. I know the sensor is supplied with 5 volts and the other wire is earth back to the engine ECU so that will make a complete circuit.
As the sensor begins begins to get hotter due to the water temperature increasing the resistance within it changes, isn't that enough for the ECU to calculate the temperature.
I only ask as planning to make a training model to teach students. Basically Im making a frame which will hold a coolant temp sensor and use a blow torch to heat the sensor, I have a 6 volt battery but just wanted to know why I need to put in an additional resistor within the circuit wiring. Also been told to put a 350 ohm resistor within it, is that correct?
Any tips on making it better for students who are 16 years old.