What are these mystery plugs in the factory wiring harness for?
I have a 2004 E250 and have these plugs coming out of the factory wiring harness that I can't find any info for. My only thought was that they could be for the rear a/c unit but I don't have an extended van with that option. And the plugs are right behind the drivers seat.
Pictures attached, not sure how the first one got turned upside down. And the last photo is a bonus unknown plug I found in the passenger side rear door, not sure what that goes to either.
6-pin rectangular plug at the B-pillar should be your RV-Upfitter connector, which should have ground, always hot, and switched-12+. I don't remember what the other pins do, if they are present in your connector. Possibly interior lights.
The 2-pin B-pillar connector is probably for the 12-volt powerpoint in the wagons.
Rear connector is definitely for a door lock switch.