Horn Troubleshooting

My horn stuck in the on position and there was no place to pull over and try to fix it. One horn finally quit, followed by the other one shortly thereafter. Dealer says horns are still good, but I need a new steering wheel, clockspring and control module that is under the clamshell on the column, to the tune of almost $4,000. The top of the airbag is slightly depressed and has been for the five years I've owned the car. It was that way when I got it. I think the warning when you attempt to lock the car with a hatch open comes from a different horn. Is that correct? I'm trying to come up with a way to test the horn(s) without pulling one off the mount. I will pull the airbag and see what is dragging, but want to test the horns first in case I need to pull the wheel and replace the other stuff. Any and all help is appreciated.

I believe his diagnosis regarding location is correct. I also believe his projected cost of repair is why I won't keep my car past 30K. If it can't be remedied for much less that is truly a car colonoscopy. PS If the horns sound, it's likely the problem is the power to said horns and when it's applied to them not an issue with the horn itself. They haven't changed much in all these years.

That "beep" horn is indeed a separate horn. I think its located near the cowl of the windshield/car battery area

ARRGH! I will drop the bottom of the front bumper and see if I can reach a horn from there. If the horn works, I will start on the steering wheel and other components. Thanks!

I'm a little confused as to which horn is being beeped without prompt. It should be quite easy to tell as the real horn is obviously louder. The steering wheel mechanism causing intermittent beeping is a problem that has manifested many years across many marques even pre airbag. If it were me I'd start at the steering wheel and look for any visual evidence of wear or unwanted contact points . Also, if the horns are on different fuses you can use that to your diagnostic advantage but based on description my bet is your horn is being triggered by unwanted circuit completion at the wheel or by the associated electronics you described in post one. In Ye' olden days it would happen frequently when weather changes were severe from hot to cold. Some goof I worked with early in my career had his go off at 3am in the hotel parking lot. He never did anything about it. Then the next day he says to me "my horn has this problem". I wanted to say, then pull a battery cable in the hotel lot buddy! This is years ago there was no onboard computer to be affected by such an action.

My question about the warning horn being different than the horns activated by pressing the airbag was merely to aid in troubleshooting the problem. Basically, if the same horns are used for both the warning and intentional activation it would be an easy test to verify the problem is in the steering wheel. Pressing the airbag will not activate the horns at all. They are dead. The only question is why? The first step is to verify the horns work. Since all features of the multi-function steering wheel work, I am reluctant to pull the wheel and replace the clockspring along with the control module until I verify the horns are good. They have a history of failing and I do not want to approach the internals of the steering until I confirm it is necessary. The parts, other than the steering wheel, are less than $500, while the horns are about $100. No point in dropping $500 replacing parts that are still good only to find out you could have fixed it for $100 on horns. I'll update as I go along.

the horns on these cars are a common failure point... locking/alarm beep is different set from the 2 (high/low tone) in the bumper. for fast troubleshooting have another set of horns (old/from another car or your local indy)

My 987.2 horn would stick. It turned out to be the Porsche part number/sticker on the back that would get sticky when hot. It would make contact with the surface behind it and over power the spring that makes the horn release. The fix was to disassemble the airbag/horn and remove the sticker---much less than $4,000. Good luck.

Your dealer seems to be really trying to reject working on your car by giving an absurd estimate. The parts for the steering wheel are available as parts - so if there was defective wiring in the wheel they could replace that small wiring harness - and while it might be pricey - it's not like replacing the entire wheel. My WAG (and that's all it is) is your horns burned up or the fuse blew from constant on. If you think about it - horns aren't intended to be on continuously - having them on continuously gives a good chance of overheating them, or burning up the buzzer contacts inside the horn. Or perhaps the module controlling them shuts them down if it believes they're not working correctly. This is all assuming you've checked the fuse.. Unfortunately, you can't access the horns themselves by taking anything off - except the entire bumper. If you had a Porsche -specific diagnostics tool (like the Foxwell NT530 w/ Porsche software) you can activate the module controlling the horns and see if they sound. You can also check the status of the switch on the horn button part of the airbag (see if it's continuously depressed.) FWIW - the usual reason for the horn button sticking is someone removed the airbag assembly and failed to put the flat cable back into the guide on the back of the assembly before pushing it back into the steering wheel. That leaves the flat cable out of place so it offsets the position of the airbag/horn-button, and the button tends to stick on when pressed. Somewhere here in some thread on the airbag/horns I posted a photo showing where the guide is on the bottom of the airbag. You might want to dig that out.

Both horns failed on my 08. Got a pair from some GM car, spliced the wire pigtail and bolted them to my Cayman bracket, last week. Total cost, $5. I hope you just need horns. They seem to be a common problem.

UPDATE! I could not set aside enough time to work on this. I finally took it to LMN Motorsports in Virginia Beach. Dropped it off last Thursday afternoon. They called Monday afternoon and said they replaced both horns and it it is good to go. Wow, they saved me over $3,000. Dealer said $3,800 for new steering wheel, clockspring and control module. These guys found the real problem and fixed it for around $600. I don't need to tell you who is going to service my Porsche from now on. I could have saved even more by doing it myself, but I found an honest shop in this evolution. That is worth the cost. I just wish they worked on Mercedes too. Thanks to all who offered advice. This is a great forum!