sure it can be that big fuse. the alternator can short and blow it. easy ! in fact that is the purpose of the biggest fuse in car.
this is and easy fix. with any voltmeter.
walmart 10 buck meter, works, any will. set to volts. 20vdc range. (or autoranged)
do head lights, they run at any time, and are most easy to diagnose. of all things on car.
turn them on, for a nice 10 amp load.
across battery reads 12.6v (lug to lug, better is post to post)
from battery neg lug to body, 0v, if see 12vdc the grounds are open. (black test lead. to battery eg, red to body. metal.
now from neg lead still on neg lug, put red test lead to each point, on fuse box, fender. all must read 12v or the fuse is blown.
bingo, im sure.
PS:
as you can see the HL fuse are in the main box. starting in 1996 up.
you will find the input to those fuses, dead. im sure. as are all mains lines dead.
many cars do same thing with battery ground lug loose at starter top bolt. or someone moved said wire (huge) to someone wrong.
seen batteries go to 0v, due to internal major failures. (straps in side)
the real 98 is here.
http://www.fixkick.com/Charging/98-Distr...-15dpi.jpg
nothing changes , in this regard, battery and the main fuses all must be hot. (at 12vdc head lights on)
see that main box 1.
see that center bus bar. all must be 12.6 hot. if not , all fuses will be dead. at there outputs.
if the alternator shorts, it blows the 80amp in 1998 car. in a flash of light , bam.