The Owners Manual (pages 12-10 to 12-12) shows three lights in that outer fender assembly, from top to bottom: tail ("tail and rear side marker"), brake, and turn.
Two wires indicates it uses a single filament bulb. When looking into the socket end that the bulb goes into, there should be only two contacts inside.
Is that the only bulb of all the rear running lights not working, or is the upper bulb (tail light) on the other side also not working?
If that's the only one, then are you sure the bulb itself is good? Also, the bulb has only small fine wires for its contacts; make sure they're in position and touching the corresponding contacts in the socket. Sometimes either could be bent out of place.
Beyond that, the two wires from the socket go into a relatively short harness that ends at a four terminal connector. There could be a problem in the wires between the socket and the connector, or even beyond, but that's unusual.