Coolant temperature sensor
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Coolant temperature sensor
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The temperature sensor is placed in the left end of the cylinder head and is in contact with the engine coolant. The sensor is of NTC type.
The control module measures the coolant temperature by supplying the sensor with 5 V from pin 39 via an integral 1.0 kohm resistor. The sensor is grounded via control module pin 22. The voltage across the resistor in the control module is proportional to the temperature of the coolant.
The coolant temperature is used to:
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calculate the injection time for pre-injection
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calculate the injection time during starter motor cranking
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calculate after-starting enrichment
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determine when the closed loop control system should be engaged
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correct the idling speed.
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If the sensor voltage is too low, diagnostic trouble code P0117 will be generated.
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If the sensor voltage is too high, trouble code P0118 will be generated.
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System reaction to a fault
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A substitute value equal to that of the temperature of the intake air on starting is selected and then increased by 1 °C (1.8 °F) for each 60 grams of air that has passed the mass air flow sensor. The substitute temperature is maximized at 90 °C.
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