Does anyone know if the 2003 Xterra's are wire prewire for foglights?

get under the front and look. If you have the connector it will work if not NO.

As long as wer'e in the topic of Fog lights...My XE Xterra does not have the factory Fog lights, but has the connector harness to connect Fog Lights, as the photo shows, my question is: Will I still need to connect a separate harness if I am going to put in after market Fog lights or could I just use the harness that's already there? would appreciate any feedback...Thanks

The factory harness probably can't handle after market lights but you could use the factory harness to control your lights instead of adding another switch. If you search you an see this discussed a lot I can't remember what gauger wire it uses and how many amps the harness can handle off the top of my head.