For starters, I took a look at the big bundle of wires that goes up the driver's side cab flange (behind the pillar). I had been assuming these were Ford wires (vs. Chinook wires), and I think that is true from what I can see. First of all, they are "Coleman" brand wires, and I don't think the Chinook wiring is that brand. Second, when they go into the cab top, they don't go into the above-headliner area like Chinook's wires tend to do. Instead, they go behind a white painted metal channel that is a Ford structural thing. At the other end I think they go down through the floor (I should look down below when it warms up).
In contrast, the Chinook wires that go to the switch panel in the above headliner area all come from the passenger side flange and are in Chinook style loom. (Oh except there is one separate wire that runs alongside that Ford bundle on the driver's side, which is a Chinook speaker wire.)
Now it does look like Chinook "handled" the Ford wire bundle on the driver's side. For one thing, it now runs through one of their plastic grommets that they use elsewhere when wires go through a hole. Also, it looks like they used masking tape to secure them on their way down to the floor (or maybe Ford did as part of the chassis cab delivery, but the grommet is Chinook. There is a matching grommet on the passenger side where they ran the gen start wires and etc. to the headliner switch panel.
I don't believe any of those driver's side wires are "Chinook" wires on my particular Concourse (except the separate speaker wire), but then I don't have the electric step. But then too, I have never actually traced that ignition controlled electric dump valve wire..... it's possible that's there.
I am now wondering if any of this wiring is detailed in the "camper kit" wiring diagrams I have (they show Ford wiring preps for chassis cab and other vans).
So in conclusion: I don't know. Since I don't have the electric step I can't look for that wire. Maybe it's worth taking the driver's side pillar off? It is a pain, but it's not THAT bad. Actually on my Concourse the driver's side one was harder than the passenger side one. That's because you have to push the rear pillar flange forward and out to get it out from behind the wall panel, and on the driver's side they had the "big" cable TV coax cabling running behind there, so I couldn't push it back very easily to "unhook" the pillar. I ended up removing that cabling because I don't do cable TV. Not that one couldn't work around it -- it was harder because at the time I didn't know WHY that side wasn't pushing back
The other thing that was a bear on the pillar removal was that little triangular cover over the top of the seat belt. Ford never meant for it to cover such a big pillar (is how I remember it). I ended up mangling one of mine (passenger side, I think - probably the first one I did), but luckily they are easy to replace (Ford part). As I remember it I then made a long tool to unsnap the other one.
Side note is that if you are planning to upgrade any of the battery wiring you'll likely want to get that pillar off so that you can get at the wiring that comes into the floor to the LVD. Another note is that you can re-attach the seat belt and drive just as normal without the pillar there, if you need to drive before reinstalling it.
Now to go stick my head/camera behind the auxilliary fuse panel.