I've been searching the web for info on using my factory-installed Upfitter Switches on my 2011 E250 E-Series. There is a lot of info out there but it can be confusing because it's often mixed in with other content. This post is specific about FACTORY INSTALLED Upfitter Switches, not about adding the Upfitter Switches after the fact. The Ford upfitter switches are optional instrument panel mounted switches (Option Code 52S) that activate powered wires located in the engine compartment to power auxillary equipment (air compressor, light bar, etc.). Pretty sure most year vans with the switches would be the same, or very similar, but I can't guarantee it.
Upfitter Switches have both an associated fuse and a relay, which are housed in the fuse/relay box at the driver's side front of the engine compartment. The fuses and relays should already be installed if you have the switches factory installed.
A useful fuse/relay chart: https://www.autogenius.info/ford-e-s...x-diagram/amp/
The actual wires to tap into are in the engine compartment as shown, toward the firewall on the driver's side. They are "blunt cut" stubs and capped. There are four wires for the switches, but they are there with other blunt-capped wires (as an aside, anyone know what the other ones are for?). Find the four wires based on the color chart below
Switches Circuit # Wire Color Fuse Size
Aux 1 CAC05 Yellow 30A
Aux 2 CAC06 Green/Brown 30A
Aux 3 CAC07 Violet/Green 10A
Aux 4 CAC08 Brown 15A
The Upfitter Switches are operational when the ignition key is in the "RUN" position only. The power to the switches is relay controlled and was designed to operate in the "RUN" mode to reduce the possibility of draining the chassis battery.