Connecting Train Horns To The OEM Horn (2015–2017 Ford F-150)
Use a MINI add-a-circuit on the horn fuse so a 2015–2017 F-150 steering wheel fires your train horns.
What you need: assembled horn kit, MINI add-a-circuit with extra 10A fuse, 18-gauge wire, optional dash toggle
2015–2017 Ford F-150
Your horn kit is assembled and you are almost ready to make noise. On this vehicle you do not need to splice a random wire under the hood — pull power from the horn fuse instead.
Getting Started
The horn fuse is only hot when the steering wheel is pressed, which makes wiring the train horns to the OEM horn much easier. This vehicle uses a MINI fuse. Use an add-a-circuit (also called a fuse tap) from an auto store or Amazon. Make sure it includes an extra fuse — if not, source a 10-amp MINI fuse.
1
Review the horn schematic
If you cannot find the horn fuse on the cover diagram, refer to year-specific fuse-box layouts for 2015, 2016, or 2017 F-150 models.
Factory horn schematic for this vehicle.
2
Disconnect the battery negative
Disconnect the negative battery terminal before you open the fuse box. This prevents shorts while you install the add-a-circuit.
3
Find the HORN fuse
Remove the engine-bay fuse box cover and check the diagram on the underside for the HORN fuse location.
4
Pull the OEM fuse and insert the add-a-circuit
Use a fuse puller or needle-nose pliers to remove the horn fuse — do not throw it away. Insert the add-a-circuit into the horn fuse slot. Place the original horn fuse in the terminals closest to the blades that go into the fuse box.
Add-a-circuit installs in the horn fuse slot.
5
Install the accessory fuse and wire
Insert the 10-amp fuse into the outer terminals of the add-a-circuit. Strip one end of the supplied 18-gauge wire and crimp it into the butt connector on the add-a-circuit lead.
6
Optional toggle, then valve power
If you want to turn the train horn on/off from the dash, route the 18-gauge wire to a toggle, then from the toggle to the positive lead on the train-horn valve. If you skip the toggle, run the wire straight to the valve positive lead.
Ground the opposite valve lead to the vehicle frame. Check for loose connections or frayed ends, reconnect the battery negative, and press the steering wheel. The train horns should honk if there is air in the tank.
Next
Connect your train horn system to a 2018–2020 Ford F-150 factory horn circuit.
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