I have a 73 SWB F100 with a 460 and c6. I swapped in a collum and all of the cruise control components from a 79 model truck that had a 460. All of my turn signals and emergency flashers work. When I hit my horn button, the relay just clicks. The 79 has a horn relay that mounts under the dash. My 73 has a horn relay that mounts on the fender well next to the solenoid.
By looking at the Haynes manual wiring diagrams, I can see that the 73 has a different horn circuit than the 79. On the 79 collum, it sends a + signal to the relay. On my 73 it sends a - signal to the relay.
Can anyone tell me what I need to do to make my horn work? I already bought a new relay and still no horn.
One guy told me I needed to eliminate the fender well mounted relay by doing some rewireing. Anyone know how to do this?
If the relay is clicking, then the steering column part is working. Find the wire coming from the horn. Hopefully it goes to the relay. Take the plug off the relay, and take a short piece of wire and run it from the positive battery post and touch it to the wire that goes to the horn. The horn should blow.
You should have some smaller wires that go from the relay plug to the steering column. We will assume they are working since the relay clicks. You should have one other heavier wire. It should be a hot wire. Take your short jumper wire and jump the horn wire to the other heavy wire that is supposed to the hot. The horn should blow. If it doesn't, figure out why that hot wire doesn't have any power. If it does blow, then the relay is not making the connection for some reason.
Dave, I finally figured out the problem.
On a 73 ford the relay is on the fenderwell next to the solenoid.
On a 79 ford with cruise, the relay is mounted behind the dash board.
My collum was sending the hot signal to the relay under the dash. The relay under the hood was getting the signal to blow. I plugged the relay under the dash in. Then put a spade connector in to the plug under the hood that tells the horn to blow. Then run a wire to my horn. Now it works great.