For 1990-2009 cars

### Diagnostic Aids

The engine may fail to reach normal operating temperature due to an intermittent operation of one of the following components:

• | Thermostat

• | Electric Fan System

For electrical inspection of the electrical fan system--Refer to Testing for Intermittent Conditions and Poor Connections.

Step | Operation | Yes | No
--- | --- | --- | ---
DEFINITION: Normal coolant temperature readings will be expected to vary within the range of 88-104°C (190-220°F).
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Verify that the engine fails to reach normal operating temperature. Is the engine fail to reach normal operating temperature? | Go to Step 3 | Go to Diagnostic Aids
3 | Inspect the surge tank for low coolant. Is there a loss of coolant? | Go to Loss of Coolant | Go to Step 4
4 | Inspect the thermostat for proper operation. Refer to Thermostat Diagnosis . Does the thermostat operate properly? | Go to Step 6 | Go to Step 5
5 | Replace the thermostat. Refer to Engine Coolant Thermostat Replacement . Did you complete the repairs? | Go to Step 6 | --
6 | Operate the system in order to verify the repairs. Did you correct the problem? | System OK | Go to Step 2