73 ECT Unstable
From SaturnWiki
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Description
The coolant temperature sensor (CTS) is a thermistor located in a coolant passage on the engine. When coolant temperature is cold the sensor has a high resistance, as temperature increase the resistance of the sensor decreases. The PCM provides a five volt signal to the coolant sensor, which is also connected to PCM ground. The PCM reads the voltage drop on the signal line to determine coolant temperature.
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Information Flag Parameters
Information Flag 73 will set if:
- CTS reading changes more than 15°C (59°F) in 100 milli-seconds.
DIAGNOSTIC AIDS
- When attempting to diagnose an intermittent problem, use the Scan Tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem. Select MALF History from Scan Tool EC menu.
- Wiggle the CTS connector. Watch Scan Tool to see if CTS reading changes falls sharply.
- Check CTS connector. Check the tightness of the female terminal grip with a spare male terminal.
- Wiggle and tug the harness. Watch Scan Tool to see if reading change sharply.
- Wiggle and tug the harness at the PCM. Lightly tap the PCM. Watch for changes in the CTS reading.
NOTICE: Information flags should be used for diagnostic purposes only. They do not necessarily indicate component malfunction/failure.
