How do you fix the horn on a 99 SL1 where is the fuse located?

The horn is right under the left headlight assy two 10mm bolts..The fuse is in the underhood fuse block right beside the battery It is labeled on the cover of the fuse block....You probably need a horn if it's inop

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If the horn still works for your alarm, (when you lock or panic) the fault is most likely the slip ring/spring in your steering wheel. That provides the negative side of he circuit to make the relay honk the horn. If every now and then the horn works, until you turn a few times, this is most likely the problem. Could also be the horn relay (under the hood, clearly marked in a fuse panel there.)