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Horn wiring question

Your old Chris-Craft electrical system can be a challenge. If it runs on "juice" pose your questions and offer your advice here.

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jbyers
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Horn wiring question

Post by jbyers » Mon Jun 22, 2015 8:26 pm

On my 58 Cavalier the horn has been removed. The three prong relay is in place but has no wires on it. There is only one wire hanging out of the end of the steering column, not connected to anything.

I know on the relay, one wire goes to the horn, one to the battery and one to the horn button. What I am confused about is that I assume the wire coming from the horn button is supposed to be hot. With only one wire coming out of the end of the steering column, where is the horn button getting it's power??? I seem to be missing a wire. I haven't taken the horn button off yet to see what's inside and prefer not to if I can help it.

Can anyone help me here?

Thanks

jnbailey71
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Re: Horn wiring question

Post by jnbailey71 » Mon Jun 22, 2015 9:07 pm

Jim- I will take a picture of my setup and post tomorrow.
Josh Bailey
1958 15' Chris-Craft Cavalier Utility K95

jbyers
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Re: Horn wiring question

Post by jbyers » Mon Jun 22, 2015 9:20 pm

Thanks

jim g
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Re: Horn wiring question

Post by jim g » Tue Jun 23, 2015 12:59 am

The relay terminals are battery, horn and ground. If its the original relay it will usually have a small letter next to the terminal to tell you what it is. The wire from the horn button is ground. It completes the circuit to energize the relay to blow the horn. The steering column has to be ground. It use to get its ground through the throttle rod. If it been replaced with a modern morse cable you will need to run a ground wire the the steering box. The casing of the horn also has to be ground to complete the circuit of the horn.

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Re: Horn wiring question

Post by jbyers » Tue Jun 23, 2015 7:23 am

It had crossed my mind that the wire from the button could be a ground, but it seemed such an unlikely design I figured I was wrong. I'll check it all out with a continuity tester before proceeding.

Thanks.

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Re: Horn wiring question

Post by jnbailey71 » Tue Jun 23, 2015 8:15 pm

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Josh Bailey
1958 15' Chris-Craft Cavalier Utility K95

jnbailey71
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Joined: Wed May 20, 2015 10:56 am
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Re: Horn wiring question

Post by jnbailey71 » Tue Jun 23, 2015 8:16 pm

Not sure if those pictures help. Red wire comes from amp gauge then the other red wire goes to the horn. The brown wire (ground) is wired to the horn it looks like.
Josh Bailey
1958 15' Chris-Craft Cavalier Utility K95

jbyers
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Re: Horn wiring question

Post by jbyers » Wed Jun 24, 2015 7:22 am

Thanks Josh. The wire from my steering column is the same color as yours so it's most likely original....... leads me to hope nothing has been modified and I can simply reconnect things to a new horn. I'll check out all the continuity first on the wires just to be sure where they are coming from.

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Re: Horn wiring question

Post by jbyers » Wed Jun 24, 2015 7:25 am

Jim,

I do still have one question. If the horn wire is connected to ground, what is the point of grounding the steering column itself? I don't see where the horn relay would need it if it's getting it's ground from the wire to the horn button.

jim g
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Re: Horn wiring question

Post by jim g » Wed Jun 24, 2015 8:32 am

Ok. Here is how it works. Hope I get it right as I haven't explained how a relay works in many years. The basics first. The horn requires power and a ground to work. The horn also pulls the most amps of any electrical part on your boat. Which is why you have big wires going to the horn as compared to the rest of the electrics. The only wires that are the same size are the wires to the amp gauge for the charging circuit. Usually 10 gauge wire size. A horn especially the old ones like the ones on our old boats are basically a direct short to create the noise.

Now if you were to hook the horn power straight to the battery which would be 10 gauge and use the horn button to complete the ground circuit which is a 16 gauge wire. A bigger wire will not fit up the tube to the horn button. Your going to get two things. One a weak sounding horn because it can't draw enough amps through the wire. If it can't draw enough current it will create heat which will melt the ground wire or burn up the horn.

Now what a relay does is it allows full voltage and the amps the horn needs to operate correctly with out going through a switch which is what your horn button basically is.

So now on the relay there are 3 terminals one is power in from the amp gauge which is battery power. Another one goes to the horn which will send full voltage to horn when the relay is energized. The 3 third terminal is ground. This is the one the connects to your switch. Your switch can be the horn button or any spring loaded push button switch.

Now when you push the horn button this completes the ground circuit and energizes the relay which completes the circuit inside of the relay which then sends full voltage through big wires so the horn can get the amps its needs to be loud and not create heat and start melting wires.

The steering column has to be ground so when you push the horn button it has ground to send to the relay.

Hope this makes sense. This relay is a very simple relay and it really hasn't been used in new vehicles since the 70's. All your modern relays are 4 or 5 prong or more. But they still basically do the same job. Some relays now are 10 to 20 prongs and do multiple functions.

The starter solenoid is in basic terms a high capacity relay made to handle a massive amount of heat and amps.

Wiring size is very critical in anything your going to wire. If you get it wrong your going to have starting problems, running problems and other systems that don't operate correctly. So then you get the idea bigger is better for all the circuits. Well yes up to a point. Then its just a waste of money.

One of the most critical sizes to get correct is the battery cable. I can't even to begin to tell you how many starting problems I've fixed just by putting the correct size battery cable on. The longer the battery cable is the bigger it has to get to get the amount of amps a starter needs to it.

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Re: Horn wiring question

Post by jbyers » Wed Jun 24, 2015 8:41 am

Thanks Jim....... I will check everything out before I try to install another horn............

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