So according to the previous owner, the cab marker lights never worked on this truck since she bought it. After I bought it from her I tried to puzzle out the problem and found the clearance light on the driver's side and the furthest left identification light both work, they were just missing bulbs. The center identification light, right identification light and passenger side clearance lights don't work. Since it's extremely easy to get to the bottom of the center ID light, I went in the cab and popped the overhead console off...the wires aren't connect to the lights. I can see the wires but they're only about 3 inches long, just barely long enough to reach the rooftop mounted lights, and they don't have connectors anymore just electrical tape over the markers. I've got no freaking clue why someone would unhook the power to 3/5 of the roof mounted lights but someone did. Any ideas how to hook the 3 disconnected cab lights back up? I'm betting they're all in similar condition, bare wires with electrical tape over them and just two pins sticking down from the roof. I could figure it out if there were pigtails or something but this one has me stumped.
Is there a way to get to the wires without taking the entire headliner out?

 

If it were me, I'd remove the headliner just because the PO may have just coiled the rest of the harness up and it could be laying in the headliner.
I'll be dropping mine in the spring time as my left side roof marker has a hole in the roof so I need to remove for rust repair. That's the bad part, the roof rusts out around the lights and or the gaskets get hard and cracked and let the water in.

 

The service manual says I have to remove the back window to get the headliner down is that right?

 

I would go on Amazon or ebay and purchase a new set of clearance lights... with the wiring harness that connects behind the pas side pillar post plug already there. Costs about $25 and comes with pre connectors so no electrical tape needed. All plug and play. Plus there are a lot if color options. Since my truck is murdered,I went with smoked lens and white cab lights.
I own a super duty so I just drop the center roof console, both sun shades and the pas pillar

 

Well in this video the guy has the head liner removed from his 06 F250 CC and the rear window hasn't been removed, so I'd say no, but I'm not 100% certain, just going by what I saw in the video.

 

Love this idea. the wiring harness is there but it's been butchered.