STDaveNW
Dave
I had the same problem on the way to NatStoc in 2012. The dealer near Omaha Nebraska found a major connection in the wiring harness had fried, melted. The place in question was below the throttle body. I saw it when they replaced it. The stealer also said there was a recall on the harness in 04. Next thinking the issue was repaired in Omaha, it happened to me again about a week after I got back to Tennessee. I found that the battery was bad, apparently not enough amps to work the relays correctly, the fuel pump would not come on and the lights would stay on, just like your description. I replaced it and I have not had any other issues. Replace the battery! before you rip out the wiring harness.
How will a weak or dead battery keep the marker lights on after ignition is off? I hope your problem stays away but that solution does not feel right. Anyway I just put a new battery in it as it sat for over 2 years.