My horns refuse to hornk! I have voltage under the steering wheels cover. At the horn connection to the horn, it reads .3 when not depressed and 12 v when it the horn is activated! Yet no noise? Doesn't this need to happen the other way around? Circuit grounds on honking?

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'79 240D
'79 300SD

those that are missed:
'80 300TD bandit
'76 300D cleta jill