check your horn fuse first thing since you have older car you may have problem at cigar lighter in ashtray check it also if it is burnt up it will blow the fuse,second look at horn and check power there with test light .also check ground older cars get dirt on grounds . then if all thats okey dokey look at horn switch . if it is in steering wheel you will need a steering wheel puller to make job easier there are copper contacts that meet copper rings on wheel to allow power to horn and cruise control swiches . I dont remember wich ones are for what you when you ground the right one horn will blow . not really to complicated at all goodluck with your test.