Horn only works when car off

[linklaw]

No, it's all factory. I did not get a chance to take the steering wheel apart yet to check the ground. When I get back to it, a friend of mine suggested trying the horn with the steering wheel turned in different positions with the car running. He thinks it might be a fault with the horn contact ring.

[Tool Pants]

On my 1988 Toyota PU a brass spring-loaded pin is used for the horn. The PU has no air bags. When that pin wears down is does not make contact with the horn contact ring when the steering wheel is in certain positions. In 18 years I have replaced that pin twice. Having the key off or on does not matter since the pin has simply worn past it's useful limit.

The airb bag/horn contact used on the 986/996 is way different. I would be very supprised if the steering wheel position has anything to do with the 3 Porsches that have horn problems. But give it a try.

[linklaw]

I tried it and no matter what position the steering wheel is in, no horn with the ignition on.

[linklaw]

I dropped the car off at my mechanic's this morning and the preliminary finding is that the ground to the horn is lost when the ignition is turned on. The guy that suggested a "floating ground" was probably on point. Apparently the horn seeks and finds a ground with the ignition off and that ground is unavailable (maybe powered) when the ignition is on. I will update when he (or I) find the fault with the ground circuit.

[linklaw]

Problem solved. It turns out the ground wire for the horn was broken inside the insulation about 1/2 inch from where the wire plugs onto the horn ring. My mechanic said that the wire comes off of the connector and then makes a 90 degree bend as it goes through the steering wheel. The wire was broken at this bend. A little soldering and the problem is fixed. Thank goodness because I have encountered a large number of horrendous drivers lately and was in desparate need of the horn.

[Loren]

That makes a lot of sense - thanks for closing the loop on this (in more ways than one ;) )

[cheetah]

Well, I am back. Finally weather where I can work on and drive the Boxster. I took off my steering wheel again, and the brown wire was loose, breaking the ground (that wire goes to ground).

BUT...

That did not fix it. When the horn is pressed (or when one manually connects the two wires with the wheel off), the relay engages but no horn. I did swap another relay, no difference.

So, now I have no horn at any time. The horn does go off for the alarm, so the horns themselves do work.

Any ideas?

[Loren]

Well, I am back. Finally weather where I can work on and drive the Boxster. I took off my steering wheel again, and the brown wire was loose, breaking the ground (that wire goes to ground).

BUT...

That did not fix it. When the horn is pressed (or when one manually connects the two wires with the wheel off), the relay engages but no horn. I did swap another relay, no difference.

So, now I have no horn at any time. The horn does go off for the alarm, so the horns themselves do work.

Any ideas?

The alarm horn is next to the battery - the two horns that are connected to the steering wheel are behind the front bumper. So there are 3 horns.

These horns die all the time so you may want to test them with a 12 volt source.

[hanayaro]

Hi there. Check all the fuses (even in the PDB) get a test light and check the power at the horn itself. If the relay is clicking, it means its working.

It will be mounted in the front USUALLY inside the bumper... or along a fender well. A car horn does not look like a typical ideal of a horn, it will be a black, Cinnamon roll looking thing with a square boxed opening, should have a 2 wire harness leading to it, use the test light there while she honks the horn, if it lights up, get a new horn, fairly cheap and easy task.