Hey guys, newbie to this forum. haha
i do car audio for a living and very rarely (unfortunately) do we get some train horn installs.
anyways, i was helping a buddy of mine install his kit on his 2013 F150 and i wanted to use a 3way toggle switch to be able to switch between his factory horn and train horn off the regular horn on the steering wheel.
i first split the factory horn wire to go to the switch input wire and the other side to the output wire, and the other side of the switch to the horn 12v wire (we found the 12v trigger wire under the hood, at the actual horn). our issue when we did this is that it was triggering the factory horn wire, but the horn actually didn’t sound, we heard them making a weird click sound but that was all.
so my next idea was to instead interrupt the negative wire with a switch because i figured there was something going on with some resistance on the other wire and negative would be better…well nope, still the same issue, the second we put just the switch in between the negative wire, we got the same result (clicking, no sound) but once the wire was reattached with no switch, the factory horn worked fine.
now my only other option that i thought of but i didn’t do was to wire up a relay under the dash to convert the negative output wire from the factory horn to positive and put that to the MIDDLE of the 3way switch. 1 side of the switch would go to the 12volt trigger wire for the train horn…but we can’t send the other side 12volt because it is suppose to send a negative trigger from inside the car.
i talked to my old boss and he thinks that Ford did something weird that when we are breaking either wire, it’s throwing off some resistance in the truck ECU, thus not sounding the factory horn.
has anyone come across this before and if so, what have you done to make it work? would really like the factory horn to be able to control either of them through a simple switch…thanks!!