bet thing to do is get the test meter out like you said first put the RED lead + on the wire to the horn and the BLACK lead - to the negitive side of the battery.

if you get a reading the horns are fooked.

if you get no reading it could be anything

horn button . you can test the button in the car take it out and test it with a meter too.

loam ?????

earth .take the horns off the mounts and clean the mounting points up for a better earth.


Only over thing does the horn/horns have a relay?????????? check it.