DS5 Sport 2013 - Alarm keeps going off

[Cupra to DS5]

Hi all,
My DS5 Sports alarm has suddenly started triggering by itself after I lock it.

It's been fine and no issues and today I opened the boot using the button in the bumper with the key in pocket then shut it all again as normal and within a short time the alarm is going off

I've cancelled it then locked it using the lock button on the key and it does it again after a short time

I've unlocked it with the key button, opened all the doors and shut them again and locked it, same issue

I've unlocked it using my hand behind the handle then started it up and driven around the block, wound windows down and up again, come back, locked it using the touch buttons on the door handle and still it's going off by itself after a short time

Any ideas?

What triggers the alarm? Is it a sudden power drain or sensors somewhere?

Anyone had the same issues?

Can I lock it without the alarm arming for now?

Thanks for any info

[Hell Razor5543]

There can be any number of things causing this (such as (but not limited to) a failed door switch or an ultra-sonics issue). It is normally possible to eliminate/prove the ultra-sonics as a cause. Find the button that switches off the ultra-sonics, switch them off (check with the owner manual, as some cars need the button to be pressed for a couple of seconds so as to limit accidental de-activation), and then lock the car. If the alarm still goes off the ultra-sonics are not a cause, while if the alarm stops going off the ultra-sonics are the likely cause. Other than this I can offer no further advice (except getting her onto a Lexia for a full diagnostics).

[Cupra to DS5]

Thanks James I'll give that a go

[GiveMeABreak]

It's very likely the alarm module. These have a finite life as the internal battery will die at some point and then it's like somebody cutting the alarm circuit - the alarm is triggered.

In almost all cases I've dealt with it's the alarm module that needs changing.

For now, and to stop the alarm activating, make sure you lock the vehicle using the key in the driver's door lock (which is stored inside the fob on hands-free versions) and do not use the remote fob or handles to lock the vehicle.

[Cupra to DS5]

Thanks for the advice Mark, appreciated
Is the alarm module a pricey job?

Is it a garage that would have to verify it being the alarm module?

Cheers

Dave

[GiveMeABreak]

Ok so be wary here. Sensors aside, there are 2 other main components the alarm ECU itself and the alarm siren.

In my experience it is mostly always the actual alarm siren that fails, because these are self-powered and use mini accumulators that normally are charged with the vehicle running. If the supply fails the alarm is triggered. If the accumulators are end of life, which will start the behaviour you are having, then you can just replace the siren. The siren also incorporates the anti-tilt sensor to detect if the vehicle is being lifted.

The siren is located on the right (UK driver's side) wheel arch, behind the wheel arch protection guards, here where I have arrowed:

[Cupra to DS5]

Aha! Thanks very much for the extra info

I'll see if I can work out what it is

[GiveMeABreak]

I've updated my post with an image ^

[Paul-R]

What exactly are the accumulators? Small SLA batteries? Capacitors? Or what?

[GiveMeABreak]

They can be any or all of the above:

https://en.wikipedia.org/wiki/Accumulator_(energy)

[Paul-R]

Yes, that's an answer in general but what is the accumulator in this particular case?

[GiveMeABreak]

Basically a rechargeable battery / batteries....

[wheeler]

Just prior to this fault starting was anyone touching any fuses in the interior fusebox?

[Cupra to DS5]

Hi Wheeler,
Nope all I did was open the boot with the button in the bumper with the key fob in my pocket. Same as always

I was wondering if it had anything to do with it being cold and the car having not been moved for a couple of days but sounds possibly like the siren batteries as per above info

Currently using the key in the fob to lock it

Read in the manual that the interior alarm button should go solid red if there is an alarm issue but it isn't doing that?

Can these batteries recharge themselves after a period of the siren not being used or are they worn out if they start causing those issues?

[GiveMeABreak]

No they are designed to recharge from the vehicles main electrical circuit, but like all batteries they have a finite life before they start to lose their capacity, until at some point they can only retain a charge for a small period of time. This then starts the siren going off intermittently.

As said, changing the siren usually resolves the issue. I don't know how old your DS5 is, but I suspect anything over 10 years old is probably pushing the batteries on these - like the direct TPMS sensors (if fitted), these too have a life expectancy of about 10 years.