Odd electrical anomaly...
 

A while back I replaced my stock steering wheel with a Cup steering wheel, Momo hub, airbag delete, and horn hook-up. I’ve since added a Prototipo as the dish was a little too deep on the Cup (Mod 7). Anyhoo, all was good until I went to try my horn the other day.. no horn. Weird, as it worked fine before. So I get home, shut down the car, pull the horn button and it works? WTH? I discovered it worked with the ignition off, but not “on”. Discovered the issue was a loose connection at the horn harness under the column cover, fixed it right up. Any one have any idea why the horn would work with the ignition off, but then not with the ignition on? Are there two horn circuits or something? Fun with Porsche wiring!!!

It's weird, as mine works with the ignition on or off. :confused: Which is opposite to every other German car I've ever owned.

I had the same symptoms. Found a broken wire inside the steering wheel assembly. Once fixed, the horn worked.

That’s what I can’t figure out. There is only one harness/hookup. The harness has 2 grounds, I plugged into one and that was the loose connection, but yet the horn worked with the ignition off. Very strange.