Join Date: Sep 2000
Location: Washington, Michigan USA
Yup, the black wire is from the horn button (grounds the relay coil, whose contacts then send 12V through the green wire to the horns). Does the relay click when you push the horn button or ground the black wire? If not, the relay is shot. If it clicks and you see 12V at the green wire but the horns don't blow, the problem is in the horns (shot or bad ground). Make sure the relay itself has a good, shiny ground where it attaches to the rad support.