Re: 3 different coolant temp sensors (CTS) Which one is what?
This was being actively discussed just a few days ago.
The spade (flat connector) and the pin are designed to work with idiot lights. They sit doing nothing as the temperature rises and then switch to complete a circuit to ground. Some use a bi metal strip to make the connection others some other mechanical point that is physically moved by the increasing temperature to contact the case.
The T head uses a fluid filled case that changes it's electrical conductivity as the temperature rises to allow a volt meter to be used as a temperature gauge. The temperature change is analog on these older cars (thermistors are used with newer digital gauges on the forth and fifth generation Camaros).