replaced the switch, still lo marker/dash/tail/clearance lights, replaced all fuses. still nothing. headlamps(high and low beam) and turn/brake/hazard lights work. Also pulled apart the dash, no wiring damage, however, the power trunk button was making the dash/tail lights flash.
I had the exact same problem-no dash lights, no marker lights. And I had already fixed the hatch harness wiring. I had replaced the rear hatch trim and the problem is the license plate lights. The two light fixtures were all corroded and one was shorting out causing fuse 30 (looking at the fuse box it's the top left one) to blow. Might want to look at them as well.
finally got into the trunk and got it popped (key hole corroded) fuse 30 is popped, licence plate lights are corroded. going to clean everything up and put it back together. will let you know if it all works out. Also, I replaced the switch because I had an extra one (parts car) that worked in the car it came out of. I am 2.5 hrs from anywhere I could get parts or diagnostics done.
Corrosion is a common problem up north....combining wetness along with road salts just literally eats almost everything on car.
Silicone grease can be your friend. Even down here in Texas I use it to waterproof and protect things all over my car. Spark plug wire boots (both ends), electrical connectors, chassis ground points, and the list goes on.
It is brake lube, but it works equally well as dielectric grease. I even use it for other things around the house such as lubing sticking water faucets. That is an AC Delco product, but there are many others that are similar.
It is one of my favorites on my workbench. Oh, and I don't contaminate the can by using the brush in the can to apply it. I use the brush to put some grease on a piece of paper and then use a screwdriver or something else to apply it. A little bit goes a long way, so use it sparingly.
Finally got it all done. nothing. So went back to the fuse box, fuse 32 (light switch) was popped [facepalm] Replaced and all working now. I still think it was the licence plate lights that popped it, but who knows.