I haven't looked at it, but I would think that you'd replace the existing horn with the relay as step 1.  You should be able to hit the switch and either see that it's working or feel it click.

Next, lay in a new wire (18 ga at least) from the battery to the relay and then on to the horn.  If neccessary, horn to ground.  Somewhere, add a fuse.

Now that you are using less current to rn the relays the horn button contacts may need some claning up. The higher current flow of the horn would make it through any corrosion or build up on the contacts while the lower current flow of the relay might not. Max

SteveRocket1 wrote on 12/31/69 at 16:00:10:


Does the horn work if you quickly touch it to the battery or another 12V source?

You have a separate button and relay?  Does that horn need a relay?

Justin said, " just wish I understood how this works".
Sorry I confused you, a relay lets you use a small amount of current flow to control a much larger amount; example, 2 amps to control 10. If you understand transisters it is much like one. Most relays can be controlled either by applied B+ and grounding either internally or at the mounting point, or control being ground with B+ always there (usually with the key on). Seems like the ones (air horns) I used to use worked fine, same with the loud snail horn I have now with the supplied relay. I haven't yet installed the one with the compressor built into the horn package. But it is loud on a bench test. The horn button on the Savage is made to control the small current our OE horn uses, when running higher load of a larger horn (or compressor) the relay saves the contact points in the horn switch from arcing and wearing away. The coil that pulls the high current points together in the relay effectively limit control side current flow and save the switch contacts from early failure. Hope this helps, if not let me know. Max

Steve:  What you need to do is make the original horn button switch the ground on the "low side" of the relay, just as though it were the original horn. The the "high side" of the relay can be used to switch either the power or ground of the new horn. As mentioned, add an adequate inline fuse in the circuit somewhere.

Max & Justin: I think you guys are having a communication breakdown: Justin: I think what Max means is that the contacts in the original horn button might pass the higher current draw (load) of a big horn; then due to corrosion or damage, fail to pass a smaller current as required by the low side of a relay. (Though I would usually think of voltage as being the force which makes a contact arc and complete a circuit.)

If you have worked on a lot of electronics stuff with relays, then you might have had the occasion to "burnish" the contacts of a relay. Like the old-time practice of "filing" the points in an old style ignition to get a few hundred more miles out of a set of points. I've "burnished" the contactors (gigantic relay contacts) of some really big relays used to switch massive amounts of juice on electromotive vehicles like locomotive power.

Thank you one and all  I will attempt to get the horn running again soon, after next weekends rear wheel change.  Did the front brake pads this Saturday, many thanks also to those who contributed to the Tech Section

Steve