So after lots of research and testing I finally finished my install. I decided to write this post because I couldn’t really find one outlining exactly how to wire train horns the way I did…although it is very possible that I just couldn’t find the post. Anyways I wanted to be able to switch between my stock horn and train horns via an illuminated toggle switch and using my stock horn pad to sound the horns.
I am using PVC horns with a few modifications off of the famous dozzerboymiller plans, haha. They are tuned to the K3LA. I decided to run them off a 10 gallon air tank through 3/8" line into a 1/2" solenoid then into a 1/2" pvc manifold with 1/4" line to each horn.
Wiring everything was simple but I made it complicated in my head so hopefully this helps someone. All you need is a simple 3 prong illuminated toggle switch with ground, load, and hot prongs. The hot prong is connected to a 12v source (+ on battery) and the ground is obviously grounded. Next you need a 5 prong NO/NC relay with 30, 85, 86, 87, and 87a prongs (I believe a fuel pump relay is what I used). This relay works by having prongs 30 and 87a connected when it’s not energized, and upon energizing the relay prongs 30 and 87 then become connected, basically it acts as a switch from one to the other. So to wire everything up you connect the positive wire coming from you steering wheel to prong 30, the positive wire coming from the stock horn to prong 87a (this allows the stock horn circuit to basically stay the same) then you take the “positive” off the solenoid (there is no set positive/negative wires on the solenoid so just pick one and ground the other) and connect it to prong 87. Finally ground out prong 86 and connect the load wire from the illuminated switch to prong 85.
This will allow you to have an illuminated switch in you vehicle so when you flip it on it will light up so you know it’s on, in case someone tries to play a joke on you. When you flip the switch it will energize the relay switching it from your stock horns (when the switch is off) to your train horns (when the switch is on), allowing you to pick one or the other.
Hopefully this helps someone. Happy scaring the “poop” outta people by honking!