Cadillac and many other US cars' headlight system is run through a switch that has a fuse built-in. So the first direct answer would be to check the switch (even if the switch fuse should be a self-resetting type - the lights should resume working in some seconds after the fuse has cooled. But I guess it can die a complete death too if the current is too much over the normal or if the switch has been around the world many times).
1986 CADILLAC FLEETWOOD EXTERIOR LIGHTING:HEADLIGHTS:SWITCH Recall Date: 04/28/1986
Summary:
THE PUSH-PULL HEADLIGHT SWITCH MAY HAVE ELECTRICAL CONTACTS WHICH ALLOW AN INTERMITTENT HEADLIGHT CIRCUIT CAUSING HEADLIGHT TO FLICKER OR SUDDENLY GO OUT. CONSEQUENCE OF DEFECT: SUDDEN LOSS OF THE HEADLIGHTS UNDER SEVERE WEATHER OR NIGHTTIME DRIVING CONDITIONS COULD REDUCE DRIVER VISIBILITY WHICH MIGHT RESULT IN A VEHICLE CRASH WITHOUT PRIOR WARNING. NOTE: ALSO, SEE NHTSA CAMPAIGN NUMBER 86V131000.
Consequence:
Remedy:
REPLACE HEADLIGHT SWITCH AS NECESSARY.
Potential Units Affected: 93317
Notes: CADILLAC FLEETWOOD
Where is the fuse box or fuse that disables the headlights and interior lights in a cadillac eldorado touring
where is the fuse for tail lights in 1988 mercury grand marquis
for the fleetwood Brogham it is located on the right fender next to the receiver dryer. there is a black cover over the fuse block. on the Fleetwood FWD is located under the hood in the center top of the fire wall. there are two separate box's. a left and right one.
fuse #17 in the fuse box located under the rear seat bench
Check the A/C fuse, that's what happened on my '85.
Under. Hood
Facing car, on left side, back behind fuse box. Should be blue.
Most likely a blown fuse
fuse bock under the rear seat.
Probably a fuse
blown fuse
There are several things that can cause your 2000 Cadillac dashboard lights to quit working. The most common cause is a blown fuse.