The ECT (Engine Coolant Temperature) sensor is a thermal variable resistor (also known as a "thermistor"). The ECT delivers a signal to the THW terminal of the Engine Control Module (ECM) which varies with engine coolant temperature. The ECM uses this signal to control the fuel injection system, the overdrive operation on vehicles equipped with electronically controlled overdrive transmissions, spark timing control, idle speed control, fuel pressure control system (if equipped), heated oxygen sensor system (if equipped) and EGR systen (if equipped)
THE ENGINE COOLANT TEMPERATURE SENSER IS A THERMISTOR A RESISTOR WHICH VARIES THE VALUE OF ITS RESISTANCE IN THE ACCORDANCE WITH TEMPERATURE CHANGES IN COOLANT.THE CHANGE IN THE RESISTANCE VALUES WILL DIRECTLY AFFECT THE VOLTAGE SIGNAL FROM THE SENSOR TO THE PCM.AS THE SENSOR TEMPERATURE INCREASES FROM HOT COOLANT THE RESISTANCE VALUES WILL DECREASE.CAUSING SENSOR TO GROUND COMPLETES CIRCUIT CAUSING COOLING FAN TURN ON.
@hotchevy1965,
I just thought I'd mention that you changed-up your description. You started out describing an Engine Collant Temperature Sensor (ECT) and ended by describing a Cooling Fan Cycling Switch. A cooling fan cycling switch is NOT a variable resistor type sensor (or thermistor). It is a SWITCH - either ON or OFF, These are used on systems where the temperature switch controls the primary ground circuit for the cooling fan relay. Vehicles equipped with these almost always have both types. One that is a variable resistor for PCM functions in controling spark advance, injector pulse width, etc. and the other controls the cooling fans. On these type of cooling systems, the cooling fans are not controled by the PCM. Others use only one sensor where the PCM ALSO controls the cooling fans. Some of these systems use 2 variable-resistor type sensors when one sensor is used for PCM functions and the other is used by the Instrument Panel Cluster (IPC) or Body Control Module (BCM to control gauge functions. The thermistor type sensors NEVER go to "full ground" to control cooling fan functions.
WELL ECT IS ABBREVIATION FOR ENGINE COOLANT TEMPERATURE SENSOR.THE ECT SENSOR RECEIVES POWER FROM THE PCM.WHEN ENGINE COOLANT TEMPERATURE INCREASES CAUSES ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE TO DECREASE CAUSES THE ECT SENSOR COMPLETE CIRCUIT.POWER FROM ECT SENSOR AND PCM TURNS ON SEND POWER TO FAN RELAYS TO TURN ON COOLING FANS.THE ECT SENSOR CONTROLS AIR FUEL MIXTURE,IT CONTROLS IGNITION TIMING AND EGR VALVE OPENING TIME.
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The ECT sensor: 1,082 views
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