Your best bets are:
* Your Owner's Manual: This is the first place to look. The owner's manual should have a diagram of the fuse box and a description of what each fuse protects.
* The Fuse Box Cover Itself: Many fuse box covers have a diagram printed on them, sometimes on the inside of the cover.
* A Repair Manual: A Haynes or Chilton repair manual for your specific year and model of Mazda MX-3 will definitely contain a detailed fuse box diagram and usually more information on locating and replacing fuses and relays. These are available online (Amazon, eBay) and at auto parts stores.
* A Mazda Dealership: As a last resort, a Mazda dealership *might* be able to provide you with a diagram, though they may charge a fee for this service.
Remember to always disconnect the negative battery terminal before working on any electrical components, including fuses.
