Lights WTF!

[0IIIIIII0]

So my driver's side parking lamp is out. But the bulb flashes when the turn signal is on

[ROLLTIDEtj]

it's probably a dual filament bulb...

[NotURMailman]

Most likely a bad groud on the marker light circuit and it is grounding itself back through the turn singal circuit when power is not applied to the turn signal circuit.
EDIT: or what he said, I was assuming you meant the side marker. Did you mean the front parking light or the side marker? Don't drive yourself nuts troubleshooting until you replace that $2 bulb!

[0IIIIIII0]

Update: Bought new bulbs. No change. Filaments appear good. ARRRRGGHHHHH.

[BlueFlame]

Clean the socket and contacts.

[Slithering_Joe]

Check the ground circuit from the bulb socket to the chassis with a meter. Dual-filament bulbs will be trouble when there is no ground. Also, check for continuity of the side marker as well.

[wushaw]

You have lost the floating ground, your gonna have to start checking wiring and the sockets on the side and the ft.

[noise_maker]

Definitely start with the unplugging the sockets and cleaning the contacts. I just had to do this to mine today as it started giving me fits. A little file or a small dremel bit works great to get the ones on the socket site. The contacts on the plug side are harder to clean. I ended up slightly bending down the contacts on the socket side a little so they make better contact with the plug side as the plugs are only one sided contacts.

If cleaning it works use some bulb or di-electric silicone grease inside the socket to keep it from happening again.

If that doesn't work check the voltage at the plug with the socket removed and go from there.
If your are unlucky enough that its not the socket / plug start tracing the wire backwards. The ground for the running light has a Y in it just inside the hood in back of the head light - you have to undo some tape but you can find it fairly easly. The Y is for the other marker on the passenger side. My passenger side lamp was doing that same thing as your driver side when I got the Jeep and it was this Y that was bad. I believe the wire (at least as I remember on my 2k) was black w/ a white stripe.

One last thing - if you do have to find the ground is not working you do have to find the spot where it is messed up and fix it. (you can't just tie it to ground - ask me how I know sometime) As mentioned above it is a floating ground and its what turns on and off when you use the turn signals with the lights on.

Good luck