Initial Inspection and Diagnostic Overview
INSPECTION AND VERIFICATIONWARNING:
SCALDING HOT COOLANT, WATER OR STEAM
NEVER remove the radiator cap under any conditions while the engine is operating. Failure to follow these instructions could result in personal injury and/or damage to the cooling system or engine. To avoid having scalding hot coolant or steam blow out of the radiator, use extreme care when removing the radiator cap from a hot radiator. Wait until the engine has cooled, then wrap a thick cloth around the radiator cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When you are certain all the pressure has been released, press down on the radiator cap (with a cloth), turn, and remove.
Cooling Fan Operation Hazard
To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine with the hood open until the fan has first been examined for possible cracks and separation.
Unexpected Cooling Fan Operation
The electric cooling fan will operate whenever the key is ON and the coolant is hot (above 105°C [221 °F]), even though the engine may not be RUNNING. Avoid placing hands, clothing, tools, or other objects in the fan blades at any time. The fan blade will also operate if the engine coolant temperature (ECT) sensor is disconnected.
1. Verify the customer concern.
2. Visually inspect for obvious signs of mechanical and electrical damage:
Mechanical
^ Coolant level and condition by operating the engine cooling system to duplicate the condition.
^ Thermostat, hose or hose clamp condition.
^ Engine cooling fan blade interference.
^ Engine cooling fan motor mounting.
^ Engine cooling fan motor blade attachment to motor shaft.
^ Damaged head gaskets or intake manifold gaskets.
^ Damaged water pump.
^ Damaged radiator or heater core.
^ Damaged radiator coolant recovery reservoir or degas bottle.
Electrical
^ Blown fuses.
^ Loose or corroded connections or damaged wiring harness.
^ Damaged constant control relay module.
^ Damaged cooling fan motor.
3. If inspection reveals obvious concern(s) that can be readily identified, service as required.
4. If the concerns remain after the inspection determine the symptoms and go to the Symptom Chart. Symptom Related Diagnostic Procedures