Help Center · Installation / Wiring
Wire a 5-pin SPDT relay so an upfitter switch chooses whether the steering wheel honks the stock horn or your train horns.
Setting the horns up on the steering is a challenge in itself. Adding an upfitter switch to the mix can be a real challenge and we would not recommend following this article if the steps below are intimidating to you. Our authorized installers can help you out with setting this up if needed. Our installer locator can be found here.
This article assumes that the rest of your kit has been installed and you are just wiring the horn up. If you are not at this step yet, please view the previous installation articles here.
Start by locating the OEM horn. On most modern vehicles, the horn is located behind the front grille area, directly ahead or to the side of the radiator. Check out the image below.
You don’t have to remove the bumper in most cases to access the OEM horns, but it does in some cases make your life easier.
Once you have located your stock horn, take a look around for a small connector going into the horn itself. These connectors almost always have two wires coming out of them. The image below gives you an idea as to what to look for.
This is where the install gets a bit tricky. To make this work, the positive wire to the OEM horn must be cut. If you are unsure as to which is the positive wire, do not cut anything. We recommend starting at the connector and going back ~6–8" so you have plenty of wire to work with. Cut the wire in half, and strip each end. If you’re unable to tell which wire is the positive wire, you can use a voltage meter to test both wires.
The Single-Pole Double Throw relay you are working with has five posts on the bottom.
The Single-Pole Double Throw relay you are working with has five posts on the bottom.
This relay is very similar to the 4-pin relays we use with some of our kits. The added post ‘87A’ is used for a second accessory. These relays are designed to switch between two circuits, when on or off. You will set this up so that one circuit is for the regular stock horn and the other is for the train horns. Both can be honked with the steering wheel, but only one at a time will honk.
The steering wheel will be used to honk each horn, and the upfitter switch allows you to switch between the two. When the vehicle is off, the train horns will not honk, as the upfitter switches are key-power on.
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