Horn Installation

If two separate horns are required, then run a power wire from an accessory terminal in the
fuse box or directly to the battery. Run it through an inline fuse then inside the truck to a dash
mounted switch then back out to the air horn. If the air horn needs more power than what the
stock wiring can handle, then the air horn should be connected to a horn relay switch. A power
wire must be run from an accessory terminal in the fuse box or directly to the battery and
through an inline fuse then back to the air horn relay contact.

The horn plugs on the opposite contact so that the steering wheel horn powers the relay (very
low power draw) and the larger power draw needed for the horn comes straight from the
battery through the relay contacts as a separate power source.

Using cutout and relays

A relay is used when the existing wiring cannot withstand the current requirement for the load,
which includes the headlights, horn, starter motor, etc. Unplug the electrical connectors that
lead to the stock horn and connect them to the harness. Connect the two sets of dual leads to
the new horns and then connect the fused end of the harness to the battery power and the
other lead to the ground. It is important to be careful when working around a battery. It is
important to not short out a connection by accident.

When should relay be used to install horn?

As discussed above, a relay is used when the wiring cannot handle the current requirement. A
horn typically uses around 24A and the stock wiring of a vehicle would be able to withstand
around 25A to 30A. When the relay is activated, it transfers the strength of the current to the horn through the wires that are designed to take the load. Since there is very little space within a steering wheel and column to run everything on the same wiring, relays must be used. Autuodrome