With two resistors, the sensor can provide a constant linear voltage representation across a wide range of temperatures. In other words, for this sensor to have a range of -40☌ (-40☏) to a high 260☌ (500☏), two resistors are required. For example, at 90☌ (194☏) the voltage could read either 0.060 volt or 3.71 volts (Figure 4).” Note the temperature to voltage “OVERLAP ZONE.” Within this zone it is possible to have either a “COLD END” or HOT END” voltage at the same temperature. A graph (Figure 3) showing temperature switching from the “COLD END” to the “HOT END” line, with increasing temperature and back with decreasing temperature is included. To cover the entire temperature range of both the CHT and ECT sensors, the PCM has a dual switching resistor circuit on the CHT input (5 volt line). “On applications that do not use an engine coolant temperature (ECT) sensor, the CHT sensor is used to determine the engine coolant temperature. There you will find the following description: That is until you actually use Ford’s material to diagnose sensor fault issues.

All sounds like a pretty standard sensor. The PCM receives the various voltage signals and equates it to a temperature value.

As the temperature increases the resistance decreases causing a voltage drop to occur on the 5 volts signal wire. A basic description of the sensor is that it is a thermistor device in which resistance changes with temperature. This 2 wire sensor (Figures 1 and 2) is checking metal temperature and is used to infer coolant temperature. According to Ford, this is a primary input in the PCM’s strategy to control Torque Converter Clutch (TCC) operation.

Torque pro extended pids explained