Reading a fuse box diagram on a Ford F-250 involves finding the fuse location, identifying the amperage and determining which circuit the fuse protects. Working from a known circuit, such as that for a power window switch, requires finding the description on the diagram and matching that to the fuse location. If the fuse diagram is in the operator manual, its key is a fuse code table linked by a location number.
There are two fuse groups on a Ford F-250: a fuse panel in the passenger compartment and a high-current power distribution box in the engine area. Each has a fuse diagram, typically printed on the vehicle in newer models. This mirrors the actual fuse area, allowing a simple visual inspection to determine location. The number and letter combinations on the diagram reflect the amperage rating, which is also printed on the fuses and reflected in the color-coding. The description on the drawing identifies the circuit protected by the fuse.
The operator's manual provides additional information, including a table with fuse amperage matched to color. Reading the manual's diagram involves matching the fuse location number on the drawing to the relay locations on the fuse code table and identifying the amperage rating and protected circuits for the appropriate location.