[dandeto]

Lets try this again, I have a 1927 Ford with a aftermarket wiring harness installed and the car now has no horn. I am going to hus a push button switch for the horn, under the seat. The fuse panel with this wiring harness has a terminal marked for car horn. There is a 40amp relay that is plugged in behind the terminal and when I ground a tester light to the car and the ignition is on, I touch the tester light to the terminal, it lights and I here the relay click. Can I take a wire from the terminal on the fuse panel and run that to my push button switch and then take a wire from the other side of the switch to the positive side of the horn? Then I would ground the negative side of the horn to the car's frame. I had purchased a separate relay to install until I located the one already in the fuse panel. I am just a little confused as I have read that I need to be using ground to sound the horn. Please advise and I appreciate the help, dandeto

[Oldguy48]

First, see if you have a wiring diagram for the aftermarket harness/fuse block you've got. That should give you the exact info you need. If that isn't available to you, I'll try to explain it. Since I don't know your expertise of electrical stuff, I'll break it down to basics. The horn relay acts as an electrically operated switch, exactly like a starter solenoid switch (Think Ford starter solenoid). One contact of the relay is connected to "hot" thru a fuse. The other contact of the relay connects to your horn. The coil of the relay requires only a small amount of current to cause the relay to energize. When the relay energizes, the contacts close and complete the circuit between "hot" and your horn. Since your relay is already designated as "horn", one side of the coil is probably already connected to a "hot" terminal, so your switch would just need to connect the other side of the relay coil to ground in order to cause the relay to energize. Typically, the horn button in the steering wheel simply grounds out the wire to the relay coil, the relay energizes, and the horn blows. What I've described is typical of horn circuits, and I can't guarantee that your set-up is the same, but it should be similar. I hope this helps you out.

[dandeto]

Thank you for the information. My fuse panel and wiring is Enos Custom Componets and after taking a better look, they have already wired the system for your horn setup with a positive wire to go to the horn and a 40amp relay with a terminal that goes to your switch. I then grounded the other terminal off of the switch and the horn works great. Oldguy thank you for the advise to contact the company that built my wiring harness. I did contact them and they responded back in an email and was very helpful. dandeto

[Oldguy48]

You are certainly welcome. I've gained a lot of great information and help from this forum, so if there is anything I can contribute (as minor as it may be) to try to help someone out, I'll do so. Also, I have found that most vendors are willing to help solve problems with their product, if you give them a shout.