Horn Relay?

[CTScott]

Originally Posted by kierf

How does one go about adding an external relay? I have a set of air horns, and it is strongly recommended I use the external relay. Previous installs I've done have been on older cars and had a seperate horn relay.

Take the feed to the existing horn and use it to feed the coil of the new horn relay (the existing horn is a one wire device, so that wire goes to one side of the relay coil and the other goes to a ground point).

Then, feed the new horn via the relay contacts (normally open). Connect an appropriately sized in-line fuse to the + terminal of the battery and from there to the common contact of the relay. Connect the normally open contact of the relay to the + wire for your new horn, and connect the - wire for your new horn to ground.