Wiring diagrams for Ford F-250 pickups are available for purchase on the FaxonAutoLiterature.com website, as of 2015. This website offers diagrams for several vehicles including Dodge, Honda, Toyota and Nissan.
On FaxonAutoLiterature.com users select the appropriate information for the Year, Make and Model drop-down boxes. Clicking the search icon yields results. Scrolling down the list of available options and clicking on the appropriate wiring diagram link produces the web page of the manual.
Manuals sell for $74 and cover various Ford F-250 models, including the Ford F-250 Super Duty XL crew cab 4-door pickup and the Ford F-250 Super Duty Lariat extended cab 4-door pickup.