Aftermakret Horn only works when car off?

I finally got around to trying to fix my aftermarket horn button on a momo prototipo. Was just the contact not being bent enough to touch the contact wheel. Anyway now it works when the car is off, but when I turn the key and power the accessories it no longer works. I put a multi meter on it and when the key is turned the wheel is getting some kind of charge. I'm bad with electronics so im not sure what it means, but if I put the positive on the wheel metal and the negative on the door negative, i get a small negative reading. If i reserve them it gives me a very small voltage. very confused on what this might be. Do I have a bad ground or something, where might that be for this? Anyway thanks for reading.

Had a very similar issue w/ our Boxster S. Turned out to be a failed ground at the wheel hub and the horn was only able to ground when the key was out and the steering wheel lock pawl was engaged. Try adding a temporary ground from the horn push to a good ground point to test.

Yeah it works if I ground it somewhere else so I have a similar problem. Guess ill just have to figure out a way to reground it or see where the ground is failing. Seems like a giant pain lol Thanks for the help

Assume you don't have a clock spring anymore? I'm sure other folks who went to non-bag wheels have figured this out...good luck on your research. Cheers.