To find it:
1. Locate the underhood fuse box: This is usually a black plastic box near the battery, often on the driver's side fender well.
2. Open the fuse box: There should be a cover you can open, possibly secured by a clip or screw. Inside, you'll find a diagram showing the fuse layout and what each fuse protects.
3. Consult the fuse box diagram: This diagram will show you which fuse is for the horn. It's often labeled "Horn" or may have a symbol of a horn. The diagram will also show the amperage rating of the fuse (usually 10A or 15A).
If you can't find the diagram: Your owner's manual will have a complete fuse box diagram. If you don't have the manual, you can often find a PDF version online by searching for "[Year] Ford Ranger fuse box diagram".
Remember to always turn off the ignition before working with fuses.