Need some horn help

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wchevron

wchevron

Joined
Oct 4, 2023
Threads
28
Messages
236
Location
Rhode Island
Since buying my '77 about 2 years ago, the horn has never worked. Had one of the guys at work install a horn button in a spare hole in the dash for the time being. Somehow he wired from the button to the horn and it workls.
Finally got around to tackling the horn in the summer. Bought a new relay, hooked everything up and nothing. I will preface this by saying I can never grasp electrical. I can never understand how the power is going through a circuit. Just doesn't click with me. Don't mind trying to figure it out but its usually more luck that I can get things working.
Anyway, when the new relay didn't work, I tried jumping things out. Ran a jumper from the battery straight to the B terminal. Didn't work, then ran a jumper from the H to the horn and pressing the steering wheel buttons it worked. Hooked the Green/red back to the relay and the horn worked. So figured the green/white wire was broken somewhere. Ran a new wire from the relay to the horn. Hooked it up and nothing. Was aggravated so left it.
Decided to tackle it today. Having no luck. I'm pretty sure I have the relay wires correct. The original plug had disintegrated so replaced that with spade connectors on the wires for now. Looking at the relay I have the g/w horn wire on the right vertical spade, g/r wire on the left vertical spade and g/y on the horizontal spade below the two others. That seems to be correct.
Took the steering wheel cover off and found the the g/y and g/r come from the relay (I'm assuming) to a plug behind the dash, then up the steering column. The g/y terminates on a board and the g/r goes up to a brass needle that makes contact with a brass ring on the underside of the steering wheel. Then from the brass ring, there are 3 wires that go to the horn buttons.
I was playing around and I disconnected the g/y at the relay and ran another wire up to the steering wheel. If I touch my jumper wire to the brass ring, underside of the steering wheel, and press the horn button, the horn works. So I figured the g/y wire had a break somewhere. So I touched my jumper wire to where the g/y is soldered to the board, hit the horn button and nothing. So now I'm lost. And really don't understand what I'm doing.
I then took my multi-meter, which I barely know how to use. At the relay if I touch the g/r, at the relay, and then a ground in the engine bay i'm getting over 12v. Same if I touch the g/y and a ground. Same if I touch either to the g/y horn wire. This is all with the ignition switch turned on.

At the steering wheel, I'm getting over 12v from the g/r, where it touches the brass needle, to a neg terminal at the fuse panel. Also over 12v from the same g/r spot to the metal, on the steering wheel, where the horn button makes a connection when you press the horn button. Also over 12v from the g/r to the g/y. From the g/y to the neg terminal on the fuse panel I get 0. Also 0 from g/y to the steering wheel metal under the horn button.

Any help would be appreciated but please explain like you would to a 5 year old. Thanks
 
A lot of time you may have an oxidized connection. I sometimes use a small wire brush to remove the oxidization. So imagine when you cut an apple and leave it on the table. The apple will turn brown....and the longer you leave it, the darker brown hence oxidation. The same happens to the connections/copper. Clean it first or reseat the terminal.

Anyhow, like Charlie mentioned the horn(momentary switch)is making ground to complete circuit. At this point all your trying to do is enable the relay. The relay has a winding(coil) when it is energized it will create magnetic field allowing the miniture plunger to close the swicth, "normally open" or "NO". Basically by pressing the horn button you are energizing the relay. If connected correctly, it allow the ground to make at the horn circuit side. I hope this makes sense.
 
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I understand the horn button completes the circuit when I press the button. But nothing is happening when I do that. So I'm at a loss as to what to look at next.

The way my brain is thinking, 12v power is coming from the fuse panel, along the g/r wire to the steering wheel. It stops there until the horn button is pressed, then power flows through the horn button, down the g/y wire to the relay and in the relay the power gets transferred to the g/w wire to the horn, through the horn and gets grounded to the ground on the other side of the horn?

if that is correct, and maybe that is where i'm messing up, then can i assume if my meter is reading 12v at the g/r in the steering column and the g/y in the steering column (when I jump them with the meter) then both wiring from the relay up steering column is good (since I'm completing the circuit with my meter) and the problem probably lies in the steering wheel connections itself?
 
wchevron said:
12v power is coming from the fuse panel, along the g/r wire to the steering wheel.
Click to expand...
No. no power goes from the fuse block to the steering wheel. The steering wheel supplies ground to the relay. The relay already has 12 volts (+) from the fuse block.
 
I'm still confused. So the steering wheel supplies the ground, which completes the circuit. It completes it when I press the horn buttons and make contact. But my horn buttons aren't making that circuit complete. So my issues is the horn buttons or maybe the wiring from the buttons to the brass ring on the underside of the steering wheel?
 
Sounds like the issue is in the steering column. Try using a long jumper wire from the relay ground and touch it to various parts of the steering shaft, especially at both sides of the rag joint in the engine compartment. Your column may not be making a good ground due to the rag joint which is non-conductive and you might need to run a short wire to jump it.
 
wchevron said:
Any help would be appreciated but please explain like you would to a 5 year old. Thanks
Click to expand...
Funnily enough, I did pretty much the same thing just a week or two ago on my '74 FJ55. I hadn't had working horns for quite some time, the old 3-wire horn relay was long gone and I had to figure out how to use a modern 4 wire relay. It took me a minute to remember the switched ground thing, so I wired the horn button output to the ground spade of the relay, the hot spade is always hot, the relay output goes straight to the horns. One of these days I'll mount that relay securely and tidy up the wires but I don't like doing wiring and I need some red wire and for now it works. There might have been 2 GR wires going through my firewall to the horn, only one was a switched ground IIRC...

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