One red flag that popos out, and that's your statement "...just bought this truck..."
What has the previous owner done in the way of modifications? Do you know this previous owner?
A fuse blows because the amp draw for that circuit is higher than the fuse rating. And by all means, NEVER install a higher rated amp fuse in attempts to prevent the fuse from blowing! The wiring that is used for that circuit is rated for a certain amp draw; installing a higher amp fuse will cause the wiring to get hot, possibly melt, and cause an electrical fire.
Get yourself an owners manual so you can identify what circuits are on fuse one. They are available for free as a PDF download, just search for one on google, or check out the sticky at the top of this forum for the link to one.
For a 2004 Ranger, fuse #1 protects: Instrument panel dimmer switch
Last edited by bucko; 07-14-2014 at 10:54 AM.