The Stovebolt Site Forums The Shop Area The Electrical Bay Horn Relay Connection

I purchased a horn relay from,Classic Parts,for my 51 Chevy short bed. The relay has three connections. There wasnt a relay installed on it when I acquired the pickup many years ago but there was a auxilary horn button on it. Now that I am attempting to hook the horn up as it should be. The new horn relay does not have a connection diagram. Again,the relay has 3 connections. The middle connection must be for the "Power", as it has a, "P" by the connector. Nothing else is labled on the relay. That leaves two other connections. The horn has two positions for connections. Though a simple connection, I dont want to fry a new relay. Does anyone know exactly how the realy and horn wiring should be connected? Your expertise would be greatly appreciated.

The 51 ADs didn't have a horn relay when they left the factory!

In 1951, there was no relay, unless you had dual horns. There is no problem hooking up a a later (like a 1954) 6v relay (or, a 12v relay if your system has been converted to 12v).

1954 horn relay
Top: lead to horn
Middle: lead from power
Bottom: lead from horn button on steering wheel

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Thanks to all who responded. Your responses definately gave me good insight. Also thanks for the pics as well. Always good to have someone that is willing to share some tech info. Will hooked it up. Tks Again!

Billy N

This simple hook-up has me twisted. I still have an auxilary horn button on my steering column until canI get my steering wheel "makeover" complete and finalbut its gona take some time.
The horn does work. However, the feed wire is going from the amp guage to the horn. Then the wire from the AUX horn botton to the hot connection of the horn, and another wire from the other connetion of horn button to horn grnd. But, whats Weird is that both connections have fire to them. I have to hook a seperate wire from one of the connections of the horn button and touch it to ground for the horn to honk. AND, pushing the horn button does not work. I have tried two horn buttons. Got any ideas?

I have not wired mine yet but plan to do so. The way I understand it- you have a hot wire from the amp gauge (or other hot source) to one post on the relay. The horn button completes a circuit to ground. The wire from the horn button goes to a post on the relay that grounds the relay and allows to power to travel from the hot lead through the relay and out the 3rd post which goes to one lead on the horn. The second horn lead needs to be grounded.

The advantage of wiring it this way is the horn button and the tiny spring within only has to act as a ground to make the relay pass current to the horn. Without a relay a much larger current flow must go thru the horn button apparatus and the tiny spring often gives up the ghost.

Chuck

Ok! I was just trying to hook it up straight without the relay for now just to have it working. Was going to install the relay once I got my steering wheel ready. Had to trace out my wires because the original wires are there plus the auxilary horn wires are there as well on top of the orgina wires, spliced from years ago. I finally just cut off all the tape from years ago so I could see exaclty where the wires are.

I am just not sure! When I hook the feed wire to one terminal of the horn, the other terminal of the horn shows to be be hot as well. This is the original horn.Is this normal on the horn or is there a short inside the horn? Shouldn't one terminal be for hot wire and the other terminal for GND?

quick test, run a ground wire to the horn ground and apply positive voltage directly to the hot terminal. If it sounds its good if it arcs it's shorted. You could also use a DVM and ohm your ground and positive terminals you should also ohm them to the case as well.

I will give it a try. TKS!

I will give it a try. TKS!

Another thought, is your horn button wired where one terminal is hooked to a good ground and by pushing the button you are a sending the ground to the relay or the horn itself? If you are not using a relay the horn has power from the ammeter and receives a ground from the horn button whether original or a add on button. If using a relay the ground from your horn button just switches the contact in the relay from open state (NO) to closed which will send power to your horn instead of a ground which means you have to ground the horn then and remove the power from the ammeter to the horn and route to your relay and run a wire from the relay to the horn from the relay output. My horns have a single terminal for power and are internally grounded so the ground is accomplished when mounted. You can also use a simple Bosch type relay which are readily available and cheap.

Whew! Wiring that horn should have been simple but it turned out to be more than expected. Was trying to wire it straight through without the relay for now until I had my steering wheel and horn contact ready for install. However, after using two different Auxilary Horn Buttons, neither would work as they should have. I went ahead and hooked it up through the steering mast. This is also original horn with two terminal connections.
With the relay terminals positioned straight down, I connected:
(1) Hot(feed) wire to B(middle) terminal of relay.
(2)Connected wire from far left Horn Relay terminal to one horn terminal.
(3)Connected GRND Wire from second horn terminal to radiator bold for GRND.
(4)Connected wire from far right terminal of relay to the wire for the steering mast and, Bingo!!! Honk Honk!!
Prior to putting steering and horn spring and horn bushing on the steering, I took a screw driver and shorted the brass steering bearing to the steering shaft to make sure the horn would honk. Then installed the steering wheel, horn spring, and horn bushing. and it worked fine. That project is done. Now pull steering wheel back off to finish its make-over. Thanks to all who provide good information.

Billy N

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