Engine Coolant Temperature (ECT) Sensor

The Engine Coolant Temperature (ECT) sensor is a 2-wire Negative Thermal Coefficient (NTC) sensor. As engine coolant temperatures increases, voltage decreases. When engine coolant temperature decreases, voltage increases. When ignition is on, PCM sends a regulated 5-volt signal to ECT sensor. When engine is cold, PCM operates in open loop. PCM will command richer air/fuel mixtures and higher idle speeds. When engine reaches operating temperature, PCM will use input from the ECT sensor for the following calculations:

• ASD Relay Shutdown Times
• EGR Solenoid On/Off Times
• EVAP Purge Solenoid On/Off Times
• Fuel Injector Pulse Width
• Fuel Injector Pulse Width During Engine Cranking
• Idle Air Control (IAC) Motor Key-On Steps
• Ignition Spark Advance Curve
• Leak Detection Pump (LDP) Operation
• O2 Sensor Closed Loop Times
• Radiator Fan Relay On/Off Times
• Target Idle Speed

The resistance values are the same as the Intake Air Temperature (IAT) sensor.