Mercury Villager 2000-2002

Testing

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  1. Let the engine cool completely before beginning the test.
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  3. Disconnect the sending unit wire.
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  5. Connect ohmmeter leads to the sending unit terminal and the negative battery terminal.
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  7. Start the engine and observe the ohmmeter. The resistance should gradually decrease as the engine warms up. When the engine has reached normal operating temperature, the resistance should be approximately 60-72 ohms. If not, replace the sending unit.

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    Fig. Checking the sending unit resistance. The resistance should decrease as the engine temperature increases

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  1. With the ignition switch OFF , disconnect the engine wiring harness from the ECT sensor.
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  3. Connect an ohmmeter between the ECT sensor terminals.
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  5. With the engine cold and the ignition switch in the OFF position, measure and note the ECT sensor resistance.
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  7. Connect the engine wiring harness to the sensor.
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  9. Start the engine and allow the engine to reach normal operating temperature.
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  11. Once the engine has reached normal operating temperature, turn the engine OFF .
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  13. Once again, disconnect the engine wiring harness from the ECT sensor.
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  15. Measure and note the ECT sensor resistance with the engine hot.
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  17. Compare the cold and hot ECT sensor resistance measurements with those in the chart. If the resistances are not within specifications, replace the sensor.

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    Fig. Disconnect the ECT sensor electrical connector to test the sensor



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    Fig. Another method of testing the ECT sensor is to submerge it in cold or hot water and check resistance



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    Fig. ECT sensor resistance-to-temperature specifications

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