That raises the question why manufacturers of new cars don't add a sensor to indicate that the electric fan is commanded, but an open circuit (no current flow). Even easier would be a high coolant temperature audible chime (some might have that). Must be for cost. Almost all new engines have aluminum heads which are very sensitive to warpage from overheating. Our engines are much more robust and can usually run until the oil overheats before they are damaged. You could rig a temperature switch in the coolant flow (ebay) and wire to a 12 V alarm in the dash, but a bit of work.
