I am trying to locate the mega fuse or fuses on my 1999 navigator.

(1) Fan Shroud
(2) Battery, RH
(3) Engine Harness
(4) Heater Hose
(5) Generator Harness
(6) Mega Fuse

That fuse is under the hood in the main fuse center.

What mega fuse ? power for ???????? Need more info

probably alternator fusible link
press the helpful button, and check video link below
Fuse link replacement for Ford Expedition 2003 5 4

If horn stops with fuse removed, the problem is in the steeringf wheel. If horn continues to sound with fuse removed, the problem is a defective horn relay (located in fuse panel under hood).

Here's a link to a site that offers advice from other Grand Cherokee owners' with similar problems. Clearly not the answer but hopefully a step in the right direction: http://forums.cnet.com/7723-7811_102-272172/the-famous-jeep-grand-cherokee-electrical-problem/

PS. Don't hesitate to contact your local Chrysler rep to see if he can't get you to a dealer that is knowledgeable about this problem and can get your vehicle repaired. The factory reps have much discrection regarding "who pays for what" so try and take advantage of that as well. Good Luck!

THE FUSE LINK TO ALTERNATOR. YOU HAVE TO DISCONNECT NEGATIVE BATTERY CABLE BUT FIRST TURN OFF RADIO BEFORE DISCONNECTING NEGATIVE BATTERY CABLE.TELL ME WHAT SIZE MEGA FUSE YOU REPLACING 40 AMP FUSE IN FUSE BOX..FORD CARRIES MEGA FUSE 175 AMP FUSE A MEGE FUSE DOES SAME JOB FUSE LINK.YOU NEED TO REPLACE FUSE LINK.FUSE LINK IS HEAVY GAUGE WIRES TWISTED TOGETHER THEN USE ROSIN CORE SOLDER AND SOLDER WIRES TOGETHER.WRAP A LOT OF ELECTRIC TAPE AROUND SOLDER WIRES TO KEEP FROM GROUNDING STARTING A ELECTRICAL FIRE. FUSE LINK LOCATED IN THE WIRE FROM THE BATTERY TO THE ALTERNATOR YOU WILL SEE WORDS FUSE LINK ON THE LINK.

Check your mega fuse. Hope you didn't try and jump it off the fuse box terminal next to the battery. Some people do this, will blow the mega fuse every time. Mega fuse is located in front of fuse box, held in by 2 bolts. Cheap fix if this is it.

CHECK THE MEGA FUSES.THE TWO MAIN BATTERY FUSES. THEY WILL CAUSE STARTING AND CHARGING PROBLEMS IF BLOWN.

check for wire or main cable close to the exhost manifoltt