Where is the horn fuse to the 99 cutlass oldsmobile

Did you check the horn relay! it is in fuse box under hood. God-Bless! if the relay is bad horn will not work. It should be be behind or near the passenger side head light.

Should be under fuse cover

There should be a fuse for the horns. Your owner's manual would give the location. It may be in the fuse/relay block under the hood. Is there another fuse panel under the driver's side dash?
There is also a horn relay in the horn circuit. This should be in the under hood relay block, but they only rarely are the problem. The most common problem with no horn is the horn switch under the horn pad on the steering wheel. The metal contact strips often get bent out of shape. You would have to pull the horn pad off to check. The pad may be held on by plastic clips, or maybe Phillips head screws from the back of steering wheel. If that part looks good, you would probably need a voltmeter or test light to start checking for power along the circuit. Sometimes just finding the horns themselves can be difficult. Maybe behind the grill, or seen from inside a fender well (behind the fender inner liner), or mounted to a lower radiator support...somewhere on the front of car.

check the fusebox under your hood for the horn relay,should be a black box close to your battery that has fuses in it

check if your using the right fuse amperage first if not than maybe its a short in the steering wheel

The horn pad has shrunk dued to the climate change through the years. The pad is made of vinyl and does retract causing this to happen. The best way to repair this since new ones are most likely discontinued is to find a used one from a state such as Arizona California were the climate is steady year round
You will have better luck with this replacement for many years to come

RF of engine compartment under hood, behind headlights.

WHAT I WOULD DO IS PUT 12 VOLTS TO THE HORN WIH A BATTERY CHARGER AND SEE IF THE HORN ITSEF IS BAD. IF IT WORKS I WOULD CHECK THE FUSES THERE ISNT A RELAY BUT THERE IS FUSES YOU SOULD BE ABLE TO LOCATE THE HORN FUSE IN YOUR OWNERS MANUAL IF NOT CHECK EVERY FUSE

check the fuse. if the fuse is ok. check the the horn relay. but usually the fuse is the culprit for horn problems like this...

the horns (two) on cars are usually located forward of the radiator and behind the grill.  Sometimes they are better reached from below the car.  And usually you need to remove some plastic shield to get to them.  The fuse in in the fuse box and should be marked as is the horn relay.