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Home >> GMC >> 1999 >> Forward Control 5.7 R, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - DTC P0100-P0134 >> DTC P0117 >> DTC P0117: ECT Sensor Circuit-High Temperature (1.9L SATURN) >> Circuit Description

Circuit Description

Engine Coolant Temperature (ECT) sensor is a thermistor located in lower coolant passage in cylinder head. ECT sensor resistance is high when coolant temperature is low and resistance drops when coolant temperature increases. PCM provides a 5-volt reference and a ground to ECT sensor. PCM monitors voltage drop on the signal line to determine coolant temperature. ECT sensor is used for fuel/ignition control, hot/cold coolant light, temperature gauge and cooling fan.

DTC P0117 will set if ECT reads greater than 284°F (140°C) when engine has been running for more than 10 seconds. DTC will set if these conditions are met after 5 seconds. ECT signal is continuously monitored when ignition is on.

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