Saw this last night, but too tired to answer.

First question where is the negative battery post connected to I.E. are you running a positive or negative ground ??? From your last sentence it looks like the horn actually does work, so you can rule a faulty horn out. Assuming you have a negative ground the next step is to take your ground wire (coming from the steering column) and check its continuity to ground. Have someone press the horn button and see if the continuity light comes on. If you do not have a continuity light find anywhere that you KNOW is hot, like the positive battery post. While the horn button is depressed BRIEFLY touch the wire to the hot source. You should get a spark. If not somewhere in the "horn parts" you do not have a ground.


1941 Chevy Master 3/4-Ton
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