I have modern Land rover defender 90 (2013) and want to add 2 Snail air horns separate to fitted horn system. i.e. separate switch on dash board. Is there a very simple wiring method which will connect up two horns and give me a switch on the dashboard. Or do I have to get into relays etc. What fuse would I need to put in line and what wire strength should I use.


  • 2 fuses, relay and suitable wiring. – Solar Mike Oct 21 '20 at 13:58
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    Welcome to Motor Vehicle Maintenance & Repair! It's really going to depend on what horns you are using and what they call for, but most likely you are going to want to run a relay to your horns through a momentary switch. – Pᴀᴜʟsᴛᴇʀ2 Oct 21 '20 at 13:59

Yes, you must:

...get into relays etc...

With air horns you also have a compressor that powers the horns, these draw a significant amount of current at 12V and it's difficult to find a switch that is both easy to press and will handle the amount of current the compressor requires. This is why relays are almost always used for horn and other high-current draw accessories. The amount of current to close the relay is relatively small and, depending on the relay itself, it can handle a very large load current.

As far as size of the relay, the size of the fuse, and the size of the wiring, you'll need to consult the specifications for the actual horn accessory you are looking at. The details will be listed there and anyone who is installing one will need to know the same thing. Many of these come in kits with the required components, relay, switch, fuse, wires, that are appropriate for the horn system.

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