were is the block heater plug on truck

The block heater is installed in a freeze plug on the engine. There should be a flat thick three conductor wire that leads to the grill area.

"Use of an engine block heater is stringly recommended if you live in a region where temperatures reach -10F (-23C) or below. For best results, plug the heater in at least three hours before starting the vehicle. The heater can be plugged in the night before starting the vehicle. The plug for the block heater is exposed in the front of the vehicle, beneath the grill. Vehicles equipped with a gasoline engine have the plug exposed on the drivers side of the vehicle; vehicles equipped with a Diesel engine have the plug exposed on the passenger side of the vehicle." The plug is a three prong grounded plug with a water-resistant rubber cap on the end of it. Ford strongly recommends in order to reduce the risk of electrical shock, do not use your heater with ungrounded electrical systems or two pronged (cheater) adapters.