I drive a 74, I installed a MOMO Sport wheel sometime back but never hooked up the horn. I want to make the car street legal, so I need some help.
Currently the horn button is connected to a black wire so that's the long and short of it.
So is there a thread that might help. I looked for a MOMO button connection thread, but no luck. I have a MOMO adaptor of course.
Is there something I need to know or do I have the wrong wire hooked up. Thanks for your help. Mike

It's a pretty simple circuit. I believe that wire completes/closes the ground side. Should only be that one wire coming up through the steering column.

Do the easy stuff first:
- Check the fuse
- ground that wire to a known good ground (with key on)
- with key off, check continuity of that wire to ground & the horn button contact to ground.

If that all checks out, you may have to take a horn(s) out to bench test it(them).

Thank you very much, I'll do just that. Mike

Does your momo hub adaptor have the horn ring on the back that touches the contacts on the steering column?

https://www.ebay.com/p/Original-Genuine-Por...6198&chn=ps

Thanks John, I'll take a look. Mike

Just touch the wire at the steering wheel to the hub (thus completing the ground connection). That will quickly tell you if the circuitry is functional or not.

Got the same issue. Touched the wire to the column and the horn works, so guessing the button is shot. Ordered a new one.

OK, so I checked out my horn button and it's fine, I also checked the black wire coming out of the column and it's hot when the key is on. Still my horns don't work. Is there a fuse or something else I need to consider? I am removing the front bumper to get access to the horns, but I think it must be something else between the horn button and the horns.
I pulled the #4 relay at the fuse box, when pushing the horn button I felt the relay working. To make sure I installed another relay and it worked the same....... But no horn. Got 2 horns on my car, neither work. thanks for your help. Mike

Any suggestions?

Check the wiring at the horn relay.
Terminal 85 is the switched ground from the horn button.
Terminal 86 is the power to operate the relay from fuse 8.
Terminal 30 power from fuse 10 to operate the horn.
Terminal 87 is the wire to the horns.

Since you can feel the relay react to grounding the wire at the steering wheel, terminals 85 & 86 seem to be good.

Make sure you have power at 30 and then check the wiring to the horns.
The horns also require good grounds.

Jim

I've been Enstine'd! Really Jim you laid it out very well, I will Take a look in the morning. You laid laid it out very well. Thanks again Jim. Mike
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[quote name='xperu' date='May 4 2018, 10:31 PM' post='2606054']
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[quote name='xperu' post='2605854' date='May 4 2018, 12:34 PM']
[quote name='Big Len' post='2605073' date='May 2 2018, 06:28 PM']
Got the same issue. Touched the wire to the column and the horn works, so guessing the button is shot. Ordered a new one.
[/quote]
OK, so I checked out my horn button and it's fine, I also checked the black wire coming out of the column and it's hot when the key is on. Still my horns don't work. Is there a fuse or something else I need to consider? I am removing the front bumper to get access to the horns, but I think it must be something else between the horn button and the horns.
I pulled the #4 relay at the fuse box, when pushing the horn button I felt the relay working. To make sure I installed another relay and it worked the same....... But no horn. Got 2 horns on my car, neither work. thanks for your help. Mike
[/quote]
Any suggestions?
[/quote]

Check the wiring at the horn relay.
Terminal 85 is the switched ground from the horn button.
Terminal 86 is the power to operate the relay from fuse 8.
Terminal 30 power from fuse 10 to operate the horn.
Terminal 87 is the wire to the horns.

Since you can feel the relay react to grounding the wire at the steering wheel, terminals 85 & 86 seem to be good.

Make sure you have power at 30 and then check the wiring to the horns.
The horns also require good grounds.

Jim
[/quote]
I've been Enstine'd! Really Jim you laid it out very well, I will Take a look in the morning. You laid laid it out very well. Thanks again Jim. Mike
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I am trying to get the car ready for inspection check, in Texas It's a 6 year for antique cars. I mostly use my car for autocross,But Still need to drive on the Road. Mike

I have a bunch of hours reworking the wiring in my 914 over the last few weeks or maybe months.

I'm pretty familiar with what is hooked to what.

We'll see how I did when I get to a point I can put a battery in it.

Jim

Before you go running down the rabbit hole of checking all this electrical stuff, realize a few things. The horn pad on the original steering wheel has only one wire going to it. That’s because the way the original horn button worked is the wire coming into the pad was hot. When you pressed the horn button you completed the circuit because there is a metal ring on the back of the steering wheel that made contact with a metal tab that it part of the turn signal/wiper electrical assembly. When you change over to a Momo wheel and Momo horn button, you no longer have something on the back of the steering wheel assembly that is making contact with the metal tab on the turn signal/wiper electrical assembly. In other words, you can’t complete the circuit. So....the back of the Momo horn button has two metal spades for electrical connections. One of those spades (doesn’t matter which) you’ll attach the wire that is part of the 914 horn button circuit (what you called the black wire). The other spade you’ll need to fabricate a short wire, maybe 3-4 inches, that has a female connector on it and the other end is just stripped back of insulation. Loosen the nut that holds the steering wheel onto the steering shaft. Under that nut should be a large wave washer. Slip the stripped back portion of the wire under the large wave washer, then tighten the steering wheel nut back down. Connect the other end of this wire, the one with the female connector, to the second spade on the back of the Momo horn button.

NOW you have a complete circuit when you press the horn button. The power is traveling through the black wire, through the horn button and to the steering shaft, which is grounded to the chassis.

My button has only one spade, But I see a metal ring on the outside of the button. Maybe for ground. I'll see what I can do with your info, it majes sense.

Mine looks like this. Snap a photo of what you have.

Mine looks like yours except the negative on mine has no spade, I just discovered the negative hole this morning. It has the ground symbol cast into the button, but no spade. I went on a search for MOMO horn buttons and sure enough there was my configuration. Maybe there is some fitting that should fit the ground hole. Thanks Mike

Well, you can disassemble the button and pop rivet a spade on there. But it still needs to make ground somewhere, so something on the back of the spade needs to find a ground.

I'm going to run a wire from the battery to the horn and check if the horn even work.
Thanks for your help Rob, I may end up at the auto electric shop before to long. For a horn? That says a lot about my electrical skill set. I did work here at NASA for a number of years........................... Not to worry, I was a cost and schedule analyst.

What you can do that’s easy is put power to the car (hook up your battery) and touch that one black wire to ground. Could be the steering shaft, the dash. As long as it’s an uncoated area of the chassis. If the horns sounds you know the code chit is working. If it is working then you could just buy a new horn button. I’m positive they’re available. Or post a ‘Want to buy’ ad in the classifieds. I’ll bet someone will sell you one of their old Momo horn buttons that they’re no longer using.

Since you describe the horn relay reacting to pressing the horn button, the horn button and it's wiring works. You have tested and verified the horn button works. The relay would not click and engage when the horn button was pushed if the horn button didn't work.

Either the horn relay is not getting power to terminal 30 from fuse 10.
Or power is not getting from the relay terminal 87 to the horns.
Or the horns don't work.
Or the horns don't have a ground circuit.

Jim

Well, I tried all the suggestions given to me except replacing the horns. I finally broke down and bought a set, tested directly to the battery and BEEP! So I installed the horns and using my MOMO wheel and button........................... BEEP. To my disbelief it was the horns. I have had this 914 for 12 years and it being my 4th 914 and I never had any horn issues. Thank you all for you help suggestions and time, maybe this thread will help others in the future. Mike

Never would have guessed it would have been the horns. Happy driving !