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    2000 Dodge Neon 2.0L SFI SOHC 4cyl

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    Coolant Temperature Sensor

    Inspect/Test/Replace

    WARNING
    Never apply an open flame to an ECT (engine coolant temperature) or IAT (intake air temperature) sensor for test purposes. This action will damage the sensor.

    A defective ECT sensor may cause some of the following problems:

    • Hard engine starting
    • Rich or lean air/fuel ratio
    • Improper operation of emissions devices
    • Reduced fuel economy
    • Improper converter clutch lockup
    • Hesitation on acceleration
    • Engine stalling

    The ect sensor may be removed and placed in a container of water with an ohmmeter connected across the sensor terminals. a thermometer is also placed in the water. when the water is heated, the sensor should have the specified resistance at any temperature. if the sensor does not have the specified resistance, replace the sensor.

    Specifications of an ECT temperature sensor. Reprinted with permission.

    The wiring to the sensor can also be checked with an ohmmeter. With the wiring connectors disconnected from the ECT sensor and the computer, connect an ohmmeter from each sensor terminal to the computer terminal to which the wire is connected. Both sensor wires should indicate less resistance than specified by the vehicle manufacturer. If the wires have higher resistance than specified, the wires or wiring connectors must be repaired.

    Specifications for an ECT sensor. Reprinted with permission.
    WARNING
    Before disconnecting any computer system component, be sure the ignition switch is turned off. Disconnecting components may cause high induced voltages and computer damage.

    With the sensor installed in the engine, the sensor terminals may be backprobed to connect a digital voltmeterto the sensor's terminals. the sensor should provide the specified voltage drop at any coolant temperature.

    Voltage drop specifications for an ECT sensor.

    Some computers have internal resistors connected in series with the ECT sensor. The computer switches these resistors at approximately 120° F (49° C). This resistance change inside the computer causes a significant change in voltage drop across the sensor, as indicated in the specifications. This is a normal condition on any computer with this feature. This change in voltage drop is always evident in the vehicle manufacturer's specifications.

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