Diagnostic Test

CHECK FOR OTHER DTCS
1. Turn the ignition on.
2. With the scan tool, read and record DTCs.
  Are there any ECT or AAT DTCs active or pending?
  
  Yes
  - Perform the applicable diagnostic procedure(s). Refer to DTC INDEX (1 OF 2) and/or DTC INDEX (2 OF 2) .
  No
  - Go To 2
CHECK THE COOLANT LEVEL AND CONDITION
WARNING:
Never open the cooling system when the engine is hot. The system is under pressure. Extreme burns or scalding may result. Failure to follow these instructions can result in possible serious or fatal injury. Allow the engine to cool before opening the cooling system.
1. Inspect the Engine Coolant for proper level and condition. Refer to COOLING SYSTEM, DIAGNOSIS AND TESTING .
  Is the Engine Coolant at the proper level and condition?
  
  Yes
  - Go To 3
  No
  - Repair the Engine Coolant level or condition problem. Inspect the vehicle for coolant leaks and repair if necessary. Fill the Engine Coolant to the proper level and ensure the proper condition. Refer to COOLING SYSTEM, DIAGNOSIS AND TESTING .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE THERMOSTAT OPERATION
NOTE:
For optimal test results, allow the vehicle to sit outside long enough to cool to ambient temperature in order to start the test with a totally cold soaked engine. With the scan tool, read the Engine Coolant Temperature degree value. If the engine was allowed to sit (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
1. Turn the ignition on.
2. If engine coolant temperature is above 82°C (180°F), allow the engine to cool until it reaches at least 65°C (150°F) or cooler before continuing with this test.
3. Start the engine.
4. During engine warm-up monitor the Engine Coolant Temperature degree value on the scan tool. The temperature value change should be a smooth transition from start up to Thermostat opening temperature. Also monitor the actual coolant temperature with a digital thermometer at or near the ECT Sensor and Thermostat positions.
  NOTE:
  As the engine warms up to operating temperature, the actual coolant temperature (thermometer reading) and the scan tool Engine Coolant Temperature degree values should stay relatively close to each other. A discrepancy may indicate an inaccurate ECT Sensor signal to the PCM.
5. As the engine warms to operating temperature, record the temperature at which the Thermostat opens.
6. Using the appropriate Service Information, determine the proper opening temperature of the Thermostat.
  Did the Thermostat open at the proper temperature?
  
  Yes
  - Go To 4
  No
  - Replace the Thermostat in accordance with the Service Information. Refer to THERMOSTAT, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE RADIATOR FOR RESTRICTIONS AND FLOW
NOTE:
The engine must be running and the Thermostat open to perform this test.
1. Check and compare the temperatures at the inlet and outlet of the Radiator. Check for proper operation of the entire cooling system. Be certain to check for proper operation of the Radiator Cap. Check for proper flow through the Radiator and anything that can cause a lack of system pressure or lack of coolant flow in the system which include air in the cooling system, proper operation of the Water Pump and drive belt, restricted Radiator core, collapsed hose restricting flow, etc.
  NOTE:
  It is normal to see a lower temperature on the outlet of the Radiator, however a very large difference could indicate a restriction in the Radiator. This condition can cause this DTC to set due to the position of the ETC Sensor in the coolant system. If necessary, compare the temperature difference with a similar vehicle.
  
  Was the difference in the temperature readings relatively larger than expected?
  
  Yes
  - Check the cooling system and Radiator for proper flow and repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace the Thermostat in accordance with the Service Information. Refer to THERMOSTAT, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .