i have an 04 fx4 and there is a plugii in the front.... i have a rough i dea what it is for but can anyone explain to me wat exactly its for

 

it's for the block heater. they help keep the block warm in super cold weather, i think all trucks sold in the midwest and northern east coast come with them stock.

 

yes, ATOM is correct... HOWEVER, if you bought it used, it could also be for a battery trickle charger..... depending if previous owner put it in. simple way to see if its for a block heater is to look at the driver side of engine, rear most frost plug port. if you have a wire going there, then it is the heater.