VW Electrics Adding an independent or new horn

Covkid: Some may be looking to see how to add an extra horn such as air horns or a klaxon horn. You can wire it differently to this if you want to make use of stock steering wheel button but this circuit is for an independent horn:

Get a 30amp relay, wire pins 85 & 86 to earth on one, and a 12v feed with switch on the other. You can mount switch in dash.That gives the relay the trigger to switch current for air horns. At this point, if you press button, relay will click.

Now for power to horns. Remaining two terminals, 30 and 87 - you just take another 12v feed using slightly heavier cable from battery to one terminal (with a fuse) and the other terminal goes to air horns. Applies to any horn that draws more than a bicycle bell. As long as you group 85 & 86 for trigger and 30 & 87 for horn supply it'll work, even if each pair is reversed. You need the relay to stop horn button burning out.

In this instance I mounted the button more over to passenger side (though still in reach) so my youngest could press it when he sees other VWs. Maplins sell these large red 'push to make' buttons for under £3. The relay and heavier gauge wire for horn itself is essential to stop current-hungry horns heating up the switch or wires. This circuit applies to anything that draws current with the relay and associated fuse matching whatever you're fitting.