Circuit/System Verification
- Turn OFF the ignition.
- Inspect the cooling system surge tank for the proper coolant level. Refer to Cooling System Leak Testing and Draining and Filling Cooling System (Static Fill LZ9) or Draining and Filling Cooling System (Vac-N-Fill) .
- If the ignition has been OFF for 8 hours or more, the ECT and the IAT should be within 15°C (27°F) of each other and also the ambient temperature. Turn ON the ignition, with the engine OFF, and use a scan tool to observe the IAT and the ECT sensor parameters.
- Use the scan tool to verify the proper operation of the engine cooling system fans.
- Verify the proper heat range and the operation of the thermostat. Refer to Thermostat Diagnosis .
CAUTION:
Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.
IMPORTANT:
A critical analysis of the operation of the thermostat is necessary to properly diagnose these DTCs.