DTC 22, ECT Sensor, Open Or Shorted Circuit: Notes

Engine Coolant Temperature (ECT) sensor is a thermistor (a variable resistor) in series with a fixed resistor in ECM. ECM applies 5 volts to ECT sensor. ECM monitors voltage across ECT sensor and converts it into a temperature reading. When engine is cold, ECT sensor resistance is high. When engine is warm, ECT sensor resistance is low. Therefore, when engine is cold, ECM receives a high voltage input and when engine is warm, ECM receives a low voltage input. DTC 22 will set if voltage input at ECM indicates either a very low or very high engine coolant temperature for at least 0.5 second.

1. Checks for an open or short to ground in White wire between ECM and ECT sensor or a faulty ECM.
2. Checks for an open in Brown wire between ECM and ECT sensor or a faulty ECM.
3. Determines if problem is a faulty ECT sensor or ECM.