For a complete wiring diagram Refer to Section 8WPossible CausesECT SENSOR - COLDECT SENSOR - HOT1. ECT SENSOR - COLDThe thermostat must be operating correctly for this test to be valid.With the scan tool in Sensors, read and note the engine coolant temperature.Using a temperature probe, measure the engine block temperature near the ECT Sensor.The engine temperature should be below 50°C (120°F).Are the readings within 7°C (13°F) of each other?YesGo To2NoCheck the wiring and connectors associated with the ECT Sensor for corrosion, damage or other problems. Repair as necessary. If no problems are found, replace the Engine Coolant Temperature Sensor.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)2. ECT SENSOR - HOTThe thermostat must be operating correctly for this test to be valid.Start the engine and bring the engine to operating temperature (thermostat open).Turn the engine off and wait 10 minutes to allow the engine temperature to stabilize.Using a temperature probe, measure the engine block temperature near the ECT Sensor.With the scan tool, select Engine, then Sensors and read the engine coolant temperature.Are the readings within 7°C (13°F) of each other?YesTest Complete.NoCheck the wiring and connectors associated with the ECT Sensor for corrosion, damage or other problems. Repair as necessary. If no problems are found, replace the Engine Coolant Temperature Sensor.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)