1. Ensure that the cooling system is full.
2. Allow the engine/radiator cap to cool.
3. Start the engine.
4. Turn the air conditioning system OFF.
5. Inspect the engine cooling fans.

Is either engine cooling fan ON?

Go to Step 2

Go to Step 3

1. Diagnose and repair the cooling fan system.
2. Verify the customer complaint.

Does the engine still fail to reach normal operating temperature?

Go to Step 3

System OK

Install the scan tool to the data link connector (DLC). Compare the scan tool coolant temperature reading to the instrument panel (I/P) cluster coolant temperature.

Is the I/P cluster coolant temperature close to the scan tool coolant temperature?

Go to Step 5

Go to Step 4

1. Diagnose and repair the coolant temperature gage system. Refer to Engine Coolant Temperature Gage Inaccurate or Inoperative .
2. Verify the customer complaint.

Does the engine still fail to reach normal operating temperature?

Go to Step 5

System OK

Caution: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the pressure cap while the engine is hot and pressure is high will cause the solution to boil instantaneously -- possibly with explosive force -- spewing the solution over the engine, fenders and the person removing the cap.

Inspect the thermostat for proper operation. Refer to Thermostat Diagnosis .

Is the thermostat operating properly?

Go to Step 1

Go to Step 6

1. Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .
2. Verify the customer complaint.

Does the engine still fail to reach normal operating temperature?

Go to Step 1

System OK