I copied this from some post (maybe 2 posts) found herein a while back:
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TIP: If you aren't crazy about the stock...meep meep horn, replace it with the Wolo or Steibel dual air horn.. I purchased the Wolo Big Boy 118 db horn because it happened to be sitting on the shelf of my motorcycle dealer. Took all of 15 minutes and it makes a huge difference. $49
Parts;
2 - 14 / 16 gauge female spade disconnectors (heat shrink variety preferred)
2 - 12" lengths of 14 gauge wire / one red and one black
2 - Posi Taps -- If you haven't used these to tap into existing connections, you are missing a very easy solution to tapping into wiring.
Shrink tubing if your connectors didn't come that way.
1- 14mm socket and stubby ratchet. No extension needed.
Good Luck.
Unplug the horn connection wires (green and brown) from the stock horn located on the driver front side of the vehicle, just next to the fog lights. Easy access under the front bumper. Press the tab on the connector and pull. Don't bother removing the stock horn. Just leave it there.
Take the two 12" lengths of wire and secure 1 spade disconnector on one side and one posi tap on the other.
Do Not attach to the horn yet. Reason is because you are going to have to use a turning motion to connect the posi tap to the stock wiring and it will twist the wires....
Now, use a dremel (or a drill if you can fit it in there) and make a hole, the size of the Wolo attachment bolt on any horizontal surface nearest the existing horn. When you get under there, it will be obvious where to do this.
Run the Wolo bolt, with a fender washer, through the top of the hole, affix the nut in the Wolo mounting bracket and tighten. I suggest you face the horn opening towards the BACK of the vehicle to avoid having rain water rush up and enter the horn.
Connect the Red wire, posi tap end, to the GREEN stock wire that you just unplugged.
Connect the Black wire, posi tap end, to the BROWN stock wire that you just unplugged. Don't cut off the stock connector. Don't need to and you may want to return it to stock some day.
The Posi tap works by sliding the wire into a slot in the tap and screwing it in so that a small needle in the posi tap pierces and wire and makes the connection.
http://www.posi-lock.com/posiplug.html
Now, Put the red wire on the positive terminal of the Wolo and the black wire to the negative terminal of the Wolo.
Go inside,, turn on key and test the horn. It will startle you. If it doesn't work, go back under and switch the wires at the horn. If that doesn't work, check all the connections. It's very simple and you shouldn't have any issues.
A relay is included with the horn but you don't need it since you are tapping into the stock horn wires and button. The relay is used for motorcycles or where you wire to a battery and intend to use a separate horn button.
It is a little tricky to get your hands in that small work area. You will have to "feel" the bolt end to connect the nut. That took the longest time.
Good Luck
Glad the horn is working well for you, Larry, but it's my understanding that the stock horn only uses a 15 amp relay and the Wolo/Stebel horns require a 30 amp one. Supposedly you won't get the full volume of the horn unless you do so.
So, this morning I installed the Wolo ($35 at Harbor Freight). Using an L-bracket I fashioned from the flat bar off a U-bolt, I was able to install the horn using the exact same bolt and hole as the stock one, which I removed. I used 12 gauge wire and connectors, quick connects to tap into the green and brown 'trigger wires' from the stock horn, and the 30 amp relay that came with the Wolo. Took the positive feed directly from the battery, tapping right into the red cable going to the jumper tap (the red knob/spring thing enclosed in a black casing) and ran that to the 30a side of the relay. Both trigger leads went to the relay's trigger sides and the relay's output (marked with #87) went through a 30a fuse and then to the horn's + terminal. The wire from the horn's neg terminal went through the small rect. holes just to the right of the horn mount, in front of the DEF container, and past the right headlight and quick connected to one of the many brown ground wires that are harnessed and run to that grounding bolt on the side wall of the engine compartment. I'll post pics of my setup when I get the time. It's plenty loud, especially compared to the stock 'meep, meep'. You would think a vehicle that cost this much would have an awesome horn..
...need vibrations...
.. so where's the Horn? 
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