I went ahead and performed the fog-light mod on my 2003 X today. The fog-lights can be used if desired (fog-light switch still works) whenever the parking lights are on. Unfortunately, I don’t have a digital camera just yet, so I’ll just give instructions (it is really simple).

The one caveat is that somewhere in the middle of 2002 the wiring for the lights switched a little. My 2003 seems to have the same wiring reported for some 2002 models. It is possible that other 2003 Xs will be different from mine as well (the 2003 service manual indicates different wiring than I have: see ElectroKen’s instructions for the 2003 based on the service manual wiring diagrams, above in thread).

Instructions for my 2003 X:

[1] Remove the steering column cover:

To do this, you’ll need to remove 3 of the 5 screws on the bottom of the steering column. These are the two at the front corners (at the edge, near the wheel) and the one at the back (near the dash on the door side) corner. You should then be able to simply remove the top plastic portion of the steering wheel cover (just a few snaps that require a slight tug).

[2] Confirm your wiring is similar:

My wiring looks like this (on the light-switch side of the steering column you’ll see 3 quick-connectors):

2 Wire connector:
1 – red/green-stripe
1 – red/black-stripe

4 Wire connector:
1-purple
1-yellow/black-stripe
1-red/black-stripe
1-blue/red

7 Wire connector:
1-green/yellow-stripe
1-green
1-yellow/green-stripe
1-red/white-stripe
1-red/green-stripe
1-green/red-stripe
1-red

[3] Connect new power source to fog-lights:

The red/black-stripe wire attached to the 2-wire connector disappears into the wiring harness along with all of the other wires. I cut this wire (red/black-stripe) close to where it disappears into the bundle of wires in the harness (this leaves some room to play with on the end that is still attached to the 2-wire connector). I then connected the longer portion of the red/black-striped wire (portion attached to the 2-wire connector) to the blue/red-striped wire leaving the 4-wire connector (using a tap connection; you don’t need to cut the blue/red-striped wire).

[4] Cover up the unused end of red/black-striped wire (the end coming out of the bundle of wires) with some electrical tape.

[5] Check light function and reinstall steering column cover.

This worked for me, and I believe another person [forgive me whoever you are] also used this technique for a 2003 Frontier. The fog-lights will not work unless the parking-lights are on. If the parking-lights are on (including low-beam and high-beam modes), the fog-lights can be turned on or off using the fog-light switch. Note (as OffroadX has pointed out) that it is illegal to drive with high-beam and fog-lights on. That said; take extra care to avoid blinding oncoming traffic when the temptation is too much for you .

I hope this helps someone. Thanks again to ElectroKen for all the help regarding the fog-light mod in all it’s various forms!