hey guys i have the PO380 code on. glow plug heater circuit A. i did some searching on here and figure I have either a bad glow plug or perhaps a whole module or something i need to replace. the last few nights have been pretty cold and the truck turns over for a long time before it starts now. does that mean its probably not just a glow plug but maybe the whole module? how do i tell for sure and what exactly is it i need to buy?? thanks!!