horn failure

[Martyn Hall]

Having left my 997.1 2006 in the driveway and gone on holiday after about a week I receive a text from a neighbour that the alarm (it was in fact the car horn) had gone off and it then sounded like it had drained the battery as it went quieter and quieter and stopped.
on my return the car started but the horn no longer works. The fuse is fine.
Any ideas?

 

[angusc]

Is your car fitted with the Piezo type alarm siren or does it use the standard horn? If you were away, was it an alarm event that sounded off the horn? does your alarm system work since your return? you can check by locking the car with windows open and then leaning in to activate the interior sensors. If the car horn sounded it must have been for a reason, especially if the car still had enough battery power to start the car....

 

[Martyn Hall]

Hi thanks for responding. It has a separate "siren" as the manual says and you are right that isn't working either and its fuse is OK as well.

 

[Martyn Hall]

Oh yes there is no sign of damage and my very nice neighbour thought it was his vehicle and walked around and there was no sign of intruders.

 

[riball]

I had the Low horn just fail a year or so back. Just stopped working and its a sealed unit so couldn't see what to "fix".
It's a DIY job if you're OK to take the bumper off and about £50 to replace said horn from on-line shops.

 

[Martyn Hall]

Thanks for the reply. Its odd the way they sounded on their own and now don't work. I wonder if there is something wrong in the wiring loom, or some sort of switch relay has failed. If I remember correctly typically the horn button switch is very low amp and when pressed triggers a relay which supplies a higher current to the horns. In the old days this used to be electro mechanical but now is probably electronic. so I think I need to know where on earth is the horn relay switch?
cheers

 

[EJWCarrera2S992]

Hi, I've had a similar problem with my 987. About a month ago, out of the blue the horn deicided to sound unaided after being locked in the garage for a couple of days. The only way I could stop it was to push the horn on the steering wheel. I thought no more of it then at 1:00 a.m it happend again so i disconnected the battery. Next day I checked things over, and all appeared fine.

A week or so later it had happend again, but I was out and this time it burnt out the horns. I replaced these and spoke PC Colchester who had not heard of it before. Neither had Paragon but they suggested that it might be the slip ring, so I had it replaced. All was fine for another two weeks then it happend again, so I left the car with PC Colchester for a week and luckily it occured whilst they had the car too.

They've just replaced the Front End Control Unit and thus far (not wishing to tempt fate) it's fine.

 

[Martyn Hall]

Hi
all useful and sounds like it might be similar problem. Bought the car from RSJ Sports car four months ago and it's now out of their warranty period. RSJ have been very good so far so I might see what they will do.

 

[Martyn Hall]

This is my first time using the forum and thank you for the response. Does anybody know what other things the Front end control unit, controls please? I haven't found anything else not working on the car.
Cheers

 

[STiG911]

Hi Martyn,
The unit controls most of the front-end electronics, so: Horn, Bonnet Release (and light), Head and Side Lights, Hazard Light Circuit, Radiator Fans.

 

[Martyn Hall]

Thanks very much Stig911, all those devices are working, so I am guessing the unit itself is OK. Have you any idea where it is located(I got as far as working out the front []) exactly?
All the best

 

[EJWCarrera2S992]

It's located on the drivers side of the front luggage area under the carpet lining, between the brake servo unit and the headlight. Basically, to get to it you'd need to remove the plastic cowling which sits in the luggage area, then fold back the carpet lining on the drivers side. You'll then see quite a thick wiring loom entering and exiting a black box, which lies under a small cover held in place with a single screw. That black box is the Front End Control Unit (FECU).

THe unit istelf is sealed, no relays involved. Also, don't assume the unit itself is okay, apart from the issue with the horns, nothing else on mine showed any signs of playing up, and no warning messages were displayed or fuses blown. Also just to advise, mine cost £250 + VAT for the part, and half an hour labour.

Just out of interest, the technician at Colchester advised me that he'd recently replaced a FECU which turned off the headlights and operated the wipers all on it's own, so it really is a 'box of tricks'.

Hope that helps.

 

[Martyn Hall]

Wow! it could be a real ghost in the machine then...
I just wondered if it was worth looking for a loose cable or something but it sounds a tad more sophisticated than that. Heh ho... looks like a somebody with a diagnostics plug is needed.
Thanks very much for the info.
Cheers