Cylinder Head Temperature Sensor
Cylinder Head Temperature (CHT) sensor is mounted in an aluminum cylinder head and measures metal temperature.- CHT sensor is a thermistor which changes resistance proportionate to temperature changes.
- Resistance increases as cylinder head temperature decreases and decreases as cylinder head temperature increases.
- Thermistor type sensors are considered passive sensors.
- A passive sensor is connected to a voltage divider network so that varying resistance of passive sensor causes a variation in total current flow.
- Voltage that is dropped across a fixed resistor in series with sensor resistor determines voltage signal at PCM.
- This voltage signal is equal to reference voltage minus the voltage drop across the fixed resistor.
- If CHT sensor signal indicates an overheating condition, PCM will initiate a fail-safe cooling strategy based on information from CHT sensor. For additional information, see FAIL-SAFE COOLING STRATEGY under POWERTRAIN CONTROL SOFTWARE.
- Using both CHT sensor and fail-safe cooling, PCM prevents damage by allowing air cooling of engine and limp home capability.