Tables and Graphs

The Cylinder Head Temperature (CHT) sensor is used to determine the engine coolant temperature in place of the Engine Coolant Temperature (ECT) sensor. 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. A graph showing the temperature switching from the COLD END line to the HOT END line with increasing temperature and back with decreasing temperature is included. 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. For example, at 90°C (194°F) the voltage could read either 0.60 volt or 3.71 volts. Refer to the table for the temperature to voltage expected values. Voltage values were calculated for VREF = 5.0 volts. These values can vary 15 percent due to sensor and VREF variations.