Horn Goes Off Randomly

[OsoMoore]

My '79 SC has been having an issue where the horn goes off all by itself. I have an aftermarket wheel (picture below).
Usually it goes off on bumpy sections of road, but sometimes when sitting at a light. I have finally pulled the relay in the front fuse box to avoid the embarrassment. That seemed to bypass the issue, and potentially eliminates some culprits.
I tried removing the wire in the center of the wheel which attaches to the horn button itself. I pulled it off and wrapped it in a sock for the rest of the drive home, so it couldn't make contact with ground. However the horn still sounded several times on its own.
I suspect the horn wire is worn somewhere and making contact with ground as the car bumps or vibrates. What I don't know is the route the horn wire runs. Does it go directly from the horn to the horn relay?

I can provide some additional pictures of the inside of the steering wheel later. Any ideas are appreciated.

[Quicksilver]

I had that happen when one of the ground wires wasn't attached at the ground point in front of the battery. (under the front lip of the frunk)
Also hitting a bump made the wipers go off.

[GH85Carrera]

My 1974 914 did that once. Just as I pulled up behind several real bikers with jackets and lots of "colors" the horn just started blaring. I ripped off the center section of the wheel and killed the ground.

Carefully pop the center section off of the steering wheel, the part you press to make it blow. You will see a little green wire. Unhook that remove the horn button part all the way. On my old 914 there was a rubber cup shaped part that had gotten old and tired. I just replaced it and problem solved.

On my 85 Carrera it has three springs to keep it centered and not honking unless I want it to.

[OsoMoore]

Back working on this again. I found that disconnecting (but insulating) the connector inside the steering wheel did not stop the erratic honking. So I suspect the wire leading to the horn button is making contact somewhere.
Does anyone recall where this where goes to? Maybe I can pull it out (with fishing line attached) and thread in a new one.

[Joe Bob]

The shorted wire can be at any wear point. IME with old VWs and 914s...it's always where you least expect it. Replace the entire line. Tape the new line to the end of the old line and pull it thru.

BTW, I had an old GF that used to go off all the time at weird times.

[GH85Carrera]

My daily driver is a 1986 El Camino with 373,000+ miles. Parts tend to wear out that were never intended to last that long. It started honking as the steering wheel was turned to certain spots. I intended to fix it one day but my wife needed to borrow it to pick up mulch at a local nursery.

Just as see pulled out of the driveway the new neighbor across the street was bending over to pick up something and the horn when toot toot. The guy turned around and waved to her, and she was mortified. I fixed the problem that afternoon.

[OsoMoore]

I took apart the steering wheel again. A few things I noted.
1) The wire from the horn button to the hub was in good shape with no abrasions.
2) The hub contact that allows the horn's signal wire to rotate seemed fine.
3) The wire from the hub contact on the car-side goes into the wiring harness and is in good shape. Can't currently locate where it comes out (fuse box area maybe?)
4) There are 3 screws that hold the horn button to the steering wheel. The wheel there is aluminum, and one of the screws is mostly stripped, so it was a little loose when I opened up the wheel.

Regarding #4, I think maybe the loose screw was wiggling around and may have been making contact across the horn's contacts. That might be what was setting the horn off. But maybe not. For now, I've removed that screw entirely. The horn button is a tight fit and missing 1 of 3 screws isn't going to cause an issue.

I'll report back once I've driven a bit, and see if I'm honked at anyone new.

EDIT: My note from last year seems to indicate that screw can't be the issue:

I tried removing the wire in the center of the wheel which attaches to the horn button itself. I pulled it off and wrapped it in a sock for the rest of the drive home, so it couldn't make contact with ground. However the horn still sounded several times on its own.