Cloud9...68

Like it says in the subject line, as long as the horn relay is connected, the horn in my 968 won't turn off. It started turning on intermittently, reminiscent of the VW van in Little Miss Sunshine (Little Miss Porsche?...), so I replaced the horn relay, and now it's on all the time. The car has a Momo racing wheel, so no airbag (yes, I placed a resistor to trick the system in to thinking the air bag is still there), and I've completely unplugged the horn switch, and it still blares as long as the horn relay is in place. When I put the horn relay back with the battery disconnected, I can hear the relay snap closed as soon as I reconnect the battery. I assume the problem was somehow caused by something I did during the install of the Momo wheel, but the problem didn't start immediately afterwards. There must be a dead short between the battery and the horn, which in principle makes it a straightforward problem to troubleshoot, but it's crazy hot in the garage, so any leads on this problem from someone who has seen something similar would be much appreciated. Thanks.

Edit: Just a bit of clarification: As I said, I can hear the horn relay click closed as soon as I connect the battery, but of course the horn doesn't go off until I turn the key to the accessory position. And I confirmed that the horn button is definitely disconnected. So the system is acting as though the wiring for the horn button is shorted somehow.

Humboldtgrin

Cloud9...68

Yikes! I looked through your thread, and I sure hope this isn't my problem! The car lives in the garage when it's not either on the track or on its way to or from the track, it NEVER sees rain, and it has spent all of its life in the South, so I would be shocked if I had any corrosion anywhere in the electrical system - I've never seen a trace of any anywhere in or on this car.

I have to believe the problem is related to my Momo wheel install, because it's just too coincidental that it started so soon after the install. It's acting as though there is a short somewhere between the horn relay and the horn switch, because the horn relay clicks closed the instant I connect the battery terminal (I have a tiny lithium ion battery, which I disconnect whenever I'm not driving the car). I think I'm going to have to figure out how to trace the wires between the horn relay and the horn switch and look for signs of a short.

Droops83

It might be obvious once you pull off the steering wheel. The hot wire to the horn button is probably pinched and is shorting somewhere in the steering hub/column. As with most cars, the entire steering shaft/column/rack is grounded via a short wire from the rack to the front crossmember, so it could be anywhere. Also, in the case of an airbag car, it could be a short within the "clock spring" through which all of the horn and airbag wiring passes through. Start by disconnecting the clock spring and see if the short goes away.

Good luck.

Cloud9...68

Well, I went in search of a source of the short, so I removed the hub adapter to have a look at the wiper connector and to get a closer look at the wires. Everything visually looks fine, with no sign of frayed insulation, pinched wires, burn marks, etc. So I put the hub adapter back on, and on a whim, tested it again. Everything works perfectly now! The horn relay no longer clicks shut when I connect the battery, so the horn doesn't go off as soon as I turn the key, and the horn does work when I connect the hot lead to ground, just like it's supposed to. So it's good that I should be able to pass inspection now, and that I have a working horn, but I sure wish I had identified the root cause, because there's nothing to prevent the problem from recurring, drawing the ire of my fellow motorists.