Caution: Under some conditions, the ethylene glycol engine coolant is combustible. In order to help avoid being burned, do not spill the antifreeze or the coolant on the exhaust system or the hot engine parts.

1. Start the engine.
2. Run the engine until the upper radiator hose feels hot.
3. Use a thermometer or other device to determine the actual engine coolant temperature. Select a method of measurement which measures the temperature of the upper radiator hose, not the actual engine coolant.

Is the measured temperature approximately equal to the temperature shown on the instrument cluster?

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Go to Step 2

Go to Step 3

1. Determine the cause for the unusual coolant temperature. Refer to Engine Overheating or Engine Fails To Reach Normal Operating Temperature in Engine Cooling.
2. Repair the cooling system.

Has cooling system been repaired?

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System OK

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1. Disconnect the pigtail connector to the engine coolant temperature (ECT) sensor.
2. Connect the red lead of a J 33431-B to terminal C of the ECT pigtail connector.
3. Connect the other lead of the tester to ground.
4. Turn the ignition switch to the RUN position.
5. Adjust the tester to 85 ohms and observe the temperature gauge in the instrument cluster.

Does the temperature gauge in the instrument cluster approximately indicate the specified value?

230°F

Go to Step 6

Go to Step 4

1. Remove the J 33431-B Signal Generator.
2. Disconnect the instrument cluster.
3. Use a J 39200 to measure the resistance between the instrument cluster connector, cavity 13 and the ECT sensor pigtail connector, cavity C.

Is the resistance greater than the specified value?

5.0 ohms

Go to Step 5

Go to Step 7

Repair the high resistance in CKT 35 between the instrument cluster connector, cavity 13 and the ECT sensor pigtail connector, cavity C.

Is the repair complete?

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System OK

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Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement .

Is the repair complete?

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System OK

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Replace the instrument cluster.

Is the repair complete?

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System OK

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