Diagnostic Test

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 cooling system for proper level and condition.
  Is the coolant level and condition OK?
  
  Yes
  - Go To 2
  No
  - Inspect the vehicle for a coolant leak, make the appropriate repairs and add the correct amount of coolant. Refer to TECHNICAL SPECIFICATIONS .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
THERMOSTAT OPERATION
NOTE:
The best way to diagnose this DTC is to allow the vehicle to sit overnight outside in order to start the test with a totally cold soaked engine.
1. Turn the ignition on.
2. With the scan tool, read the Engine Coolant Temperature degree value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
  NOTE:
  If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is reached.
3. Start the engine.
4. During engine warm-up monitor the Engine Coolant Temperature degree value. The temperature value change should be a smooth transition from start up to normal operating temp 82°C (180°F). 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.
5. Using the appropriate Service Information, determine the proper opening temperature of the thermostat.
  Did the thermostat open at the proper temperature?
  
  Yes
  - Go To 3
  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 .
ECT SENSOR OPERATION
Was the digital thermometer readings relatively close to the scan tool reading for the ECT Sensor?

Yes
- Go To 4
No
- Replace the Engine Coolant Temperature (ECT) Sensor in accordance with the Service Information. Refer to SENSOR, COOLANT TEMPERATURE, REMOVAL AND INSTALLATION .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
COOLING SYSTEM OPERATION
1. Check the temperature reading at the inlet and outlet of the Radiator.
  NOTE:
  It is normal to see a lower temperature on the outlet of the Radiator, however a very large difference indicates a restriction in the Radiator core. This can cause this DTC to set due to the position on the ETC Sensor in the system.
  
  Was the difference in the temperature readings relatively larger than expected?
  
  Yes
  - Replace the Radiator in accordance with the Service Information. Refer to RADIATOR, ENGINE COOLING, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Powertrain Control Module in accordance with the Service information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  - Test complete.