Where is the mega fuse on a 1999 navigator?

The 1999 Lincoln Navigator doesn't have a single "mega fuse" in the way some vehicles might have a single large fuse for the entire power system. Instead, it uses a network of fuses and relays, some of which are high-capacity. The location of these high-capacity fuses and relays varies depending on what circuit you're trying to troubleshoot.

To find the fuses you need, you'll want to consult your owner's manual. It will have fuse box diagrams showing the location(s) of the fuse boxes (there's usually one under the hood and one inside the cabin) and what each fuse protects. If you suspect a problem with a major system (like the entire electrical system or starter), you'll need to check several fuses and relays, not just one "mega fuse".