Alarm won't stop going off - single beep when locking

Guys (and gals) Car has been fine up until this morning, parked it up about 10am and headed out into the city, got a call from the wife about 11.30 to say my alarm was going off and wouldn't stop. Basically it just won't stop going off, she tried everything I could think of including starting the car, driving it back and forth, letting the engine run for 5 minutes, checking all the doors were firmly closed as well as the boot and bonnet. Everything shut. She then noticed that when she relocked the car, with a single push of the lock button, that the lights flashed twice and then the horn beeped once. I understand that you can set the alarm and turn off the interior sensors and in return you get the single horn sound, but this is not what she was doing. Called Porsche Assist (thankfully I have a warranty) and they sent the RAC out who tried everything I had already told her to try and ended up taking my car to a secure parking facility near by where it could be left unlocked until the dealer is open on Monday and can take a look at it. Was wondering if anyone here had experienced the same thing? Anyone know what can cause the horn to beep once when locking the car? Would like to get the car back tomorrow and have a go at trying to diagnose the problem and fix it! One thing to note is that I did re-install the PCM unit last weekend (car has been fine though for a week) and I understand there is an alarm wire on the stereo? Anyone got a picture of this, maybe it is something I should check, but I can't see why something like this would cause the alarm to go off continuosly!? Plus the car has been fine for over a week since i put the PCM unit back in. Thanks

Did you check the glovebox was closed properly too? Just trying to think what might tell the alarm system that it's not activated properly. Rich

Hmm - sounds like you've tried a lot. Haven't come across this myself but if I depress the lock on the key fob twice in quick succession I get the single pip of the horn. On other cars I've owned I had to press lock twice to get the doors to deadlock so do this as part of a habit now (FYI my doors are always locked when I do this....). Incidentally did your wife do anything prior to the alarm going off? Also did you try disconnecting the battery; leaving it for a few mins and then reconnecting and seeing if the alarm started to go off?

Pressing the button twice in 3 seconds locks the car without the interior sensors on and you get a single horn sound, that is normal - but not what she was doing. Didn't check the glove box as I wasn't here. Am going to go and see if I can try some things up at the car park tomorrow! Will try glove box and centre console box, will also try disconnecting the battery etc. Any more things to try?

Actually now that I think of it when I bought the car the guy mentioned that if the alarm goes off you need to follow a bit of a rigmarole to get it to stop. He said that you need to open the bonnet shut it fully lock and alarm the car. Then unlock it get in and start it. I have no idea if this is true mind you and you'll just have to trust me that I've not just thought of a completely random set of things to do for my own amusement....

My alarm keeps randomly going off too. I spoke to someone technical at Porsche and they mentioned that the key may not be 'connecting with the car'. They suggested locking as normal and then opening with the key in the door method, then put the key in the ingnition and turn to position 1 within 10sec. This does work, for a while :frustrated: This may not help you though if you can't even lock the car...

Car locks and seeminly arms the alarm (as it keeps going off). Time between the alarm going off varied between 10 minutes and nearly an hour (after it was started and moved back and forth). The car is then being left locked and "armed" and then the alarm decides to go off!

Time for a new locking module by the sounds of it... I had this, and then couldn't lock the car (not good when you park in the street!) Only solution was a trip to the OPC and a new lock module (fitted in the passenger door) - oh, and £300 + off the chip and pin!

Do the courtesy lights go out straight away when you lock it?

Couldn't tell you as it was the wife who was trying to lock it and get the alarm to stay off, then here and the RAC man that Porsche Assist sent out. Covered under the warranty I hope!?!? Apparently the module under the passenger seat was lose, not fixed to the car just attached by the wires!?

Turned out to be the control unit under the seat, replaced under warranty

Pleased to hear it. :thumb:

Just in case anyone else looks at this thread. The alarm can tell that something is not closed correctly by giving a single beep of the horn when you lock the car. If you have checked all of the usual suspects like the centre console lid, glovebox etc then look and see if you have or did have an aftermarket stereo. If so then there is a brown wire with a blue stripe that is on a connector that makes a circuit with the left hand side of the head unit. The original stereo would have had a plastic pad on the same side which the connector touches when the stereo is in situ. This is the alarm circuit for the stereo. If you have an aftermarket stereo then tape off this connector with insulating tape. If the car previously had an aftermarket stereo but the original hsas been replaced then check that the connecter is in fact connected !This should stop the beep when you switch on the alarm.