To find the correct fuse:
1. Consult your owner's manual: This is the best resource. The manual will have a fuse diagram showing the location of the fuse box(es) (under the hood and usually one inside the cab, often under the dash) and which fuse corresponds to each power point.
2. Locate fuse boxes: The 1999 F-250 likely has at least two fuse boxes: one under the hood and one inside the cab.
3. Examine fuse labels: Once you've located the fuse box(es), carefully examine the labels on each fuse. They might list what circuit each fuse protects (e.g., "Power Outlet," "Accessory Power").
Without your owner's manual, it's impossible to give a precise location. Searching online for "1999 Ford F250 fuse box diagram" might yield a diagram, but even those can vary slightly depending on trim level and options. Always use the owner's manual as the primary source for this information.
