S4 Alarm


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May 25, 2004
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My alarm keeps going off when car is locked. I can hear a noise coming from the drivers side rear quarter panel, just behind the light in the boot. It's a strange sound like an electrical croak, it's a faint sound not loud. I know that sounds funny, but it's the best way to describe it i think /ubbthreads/images/graemlins/grin.gif

I've tried unlocking and locking the car, turning the ignition on and re-locking the car again after all this the alarm still goes off. When i unlock the car but dont open any doors and then the car re-locks itself, thats the only time the alarm doesn't go off by itself......

Any help would be appreciated as it is doing my head in now. /ubbthreads/images/graemlins/burningmad.gif

Had quite a few probs with my S4 Alarm. Main dealers ( or Vag Com?) can run a lot of tests and diagnostics to tell you what could be the cause. I had the main control unit changed on mine twice under warrantey and the ultrasonic sensors sensitivity adjusted, to fix the problem.
having the same problem with mine just now. The siren for the alarm is in the boot at the rear quarter panel.

Cars going in for a service on Wednesday so getting them to have a look at it and will let you know.

bit strange mine as after locking the car 50 mins later the siren only goes off (no hazards or anything else). It goes off for 5 mins before resetting.

What I've had to do is lock the car from the inside using the button on the drivers door. If I do this with the passenger door open I can then close it which leaves all 4 doors locked.

Means the alarms not set though.

Hopefully nothing too costly.
That sounds like exactly what mine is doing. Approx 50 minutes give or take, after the car has been locked the alarm goes off without the hazards flashing???? Very annoying!!! If you find out anything it would be appreciated, if i haven't taken mine in by then /ubbthreads/images/graemlins/crazy.gif
The most likely cause for this type of spurious problem seems to be the backup batteries in the siren module. When these start to no longer hold charge then the alarm will set itself off. Apparently the whole unit is around £80 and the batteries can't be easily be replaced seperately. Alternatively you can disconnect the siren unit which leaves the immobiliser working.
Thanks for the info, i'll get it checked out when it goes in for a service next week. In the meantime i've disabled the sensor located on the pillar. I think thats what it does /ubbthreads/images/graemlins/blush.gif and that seems to have done the trick....For now!!!
If that works then it won't be the battery problem, but more like an oversensitive sensor in the cabin. I found the problem went away if the car was being used regularly and the nights were fairly warm. The problem first came to light when I wasn't using the car that much and the nights were really cold. It would choose about 3am to go off repeatedly until I disconnected the battery. Which all makes sense if it is a battery backup problem.
That worked with mine also (this switch turns off the ultrasonics) so it could be worth having the sensitivity turned down on them. Mine has not gone off since this has been done.... so far at least!

Mine seemed to go off when it was very warm ?
Yes mine only started since we've had this warm weather come to think of it. So far though with the sensor inside off it has been fine. /ubbthreads/images/graemlins/beerchug.gif
Well got the car back from Audi.

They say its a fault with the siren. They also tell me there's no batteries within the siren and its definitely the siren that needs replaced.

As said earlier if the alarms not going off when the interior sensors are de-activated (button on the door pillar) then its probably not the siren.

Just as an aside when I initially called them Audi did tell me to de-activate the interior sensors to see if this would help. Also told me to press the other button next to it to de-activate the tilt sensor. Only have one button says I.

Does anyone know should I have had one its a March 2000 model.

Lastly Audi wanted £150 to replace the siren. Siren is about £70 plus the VAT from them.

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