Purchased 1980 home, exterior outlet not working
The fact of the wires being left in the box but not capped is practically proof that they are not hooked up to anything on the other end.  

The reason is, no sane person would energize wires that are just tucked into a box without capping.  In fact I believe energizing a set of wires to nothing is a code violation, even if they are capped.  Which they are not.

So it'll be a bit of a bug hunt to find the other end of this cable.