Alarm!

dj_efk

A2OC Donor
United-Kingdom
Audrey’s alarm has developed an annoying habit of kicking off at inopportune moments - like at 3am for example. It’s random in that it doesn’t always do it when I lock the car overnight, other times it will go off within a few minutes. We are due to lend the car to visiting friends this weekend so it would Ben great if they could lock the car with n alarm until I sort it.

Scanning for faults consistently points to the fault lying with the rear interior glass breakage sensor. So I have two questions for you all:


1) How do I disable the alarm temporarily until I can fix it properly - is there a fuse I could pull?

2) Where is the offending sensor located and has anyone experienced the job of replacing it?


As it’s electronics and also because I may need a part, paging @timmus @Clackers @A2Steve & @Ami in the first instance.
 
Morning David,

I know I’m not on your list above so hope you don’t mind me jumping in. As you know everything starts with a scan as there might be an obvious reason why the alarm is being triggered. Investigate Ch46 and it should provide you with where these triggers have originated. It could be a faulty wire near the service flap plunger etcetera. I know your have VCDS so please do a scan when possible.

I had this exact issue with my first FSI a few years ago where the alarm would randomly trigger and annoy the neighbours and of course me having to get out of bed to investigate.

It turned out to be a failing battery within the alarm module and replacing the module rectified it instantly. There are threads on here where members have managed to open up the module and solder a replacement battery into the module. This of course would be the best solution I suppose as any used module could quickly present the same issue. That said I did replace the whole module for a used one and it was fine.

As for a temporary fix, there is no separate fuse for the alarm, looking at the wiring diagram it reveals the alarm module is powered by the CCCU. Of course removing the fused feeds to the CCCU would result in many other areas of your A2 becoming unusable and not recommended:

0FD151C8-DBD0-4B83-BF12-6FE14C12920D.jpeg


What will work though is simply unplugging the module itself which can be done reasonably quickly. It sits behind the off side luggage space panel below the fuel flap mechanism. I’m sure someone posted on here a few months ago that they managed to disconnect the module without removing the luggage space panel, going through the rear light cover aperture. Not sure my hands would get down there.

Start off with a scan as it could be something else.

Additionally if you scroll down you’ll see a list of similar threads where members have had the same issue with varying solutions detailed within them.

Hope this helps.

Kind regards,

Tom
 
Hi David

I’ll check to see if I’ve got an alarm on the shelf, but if I haven’t I can get one off for you on Saturday. It will be the later style to match yours, although you can fit either.
 
Thanks guys - as above, I've scanned already (easy to do with CDIS!) - and the fault is with the rear interior glass breakage sensor; so I need to know where that is located on the car so I can investigate and if necessary replace. One would assume in boot area but assumptions can be dangerous!

Tom, thanks for the info on fuses / disconnecting the alarm itself.
 
David,

Have a look at this thread, specifically Post #8 where is @ajsellors explains the same fault that in his instance was cured by ensuring the press stud type fixing was securely fitted. Failing that this thread might be of help where Mike @Skipton01 suggests a resolution. As I said at the beginning, scan results alway assist and might even avoid unnecessary purchases.

Kind regards,

Tom
 
I get the same sometimes and same fault code as well, along with 2 more. As a temporary fix, remote lock the car, then remote unlock it, don't open any doors, then in 30s the car auto locks it again. This usually works for me.
 
Thanks guys - as above, I've scanned already (easy to do with CDIS!) - and the fault is with the rear interior glass breakage sensor; so I need to know where that is located on the car so I can investigate and if necessary replace. One would assume in boot area but assumptions can be dangerous!

Tom, thanks for the info on fuses / disconnecting the alarm itself.
CDIS is, I'm sure handy, but it's diagnostics are not an equivalent of a VCDS or OBD Eleven scan, (other scan tools are available).
Mac.
 
You can deactivate the alarm system until you solve the problem. ;)
Check you coding for 46 module and RETRACT 10 from it. That will deactivate the alarm.
My coding was 06730 and 06720 deactivated the alarm. I have used this for a long period of time that the car was not used, to lower the battery consumption. The interior sensors alarm deactivation button light will be on all the time.
 
I get the same sometimes and same fault code as well, along with 2 more. As a temporary fix, remote lock the car, then remote unlock it, don't open any doors, then in 30s the car auto locks it again. This usually works for me.
I have tried that - but the alarm seems to auto-arm!
 
David,

Have a look at this thread, specifically Post #8 where is @ajsellors explains the same fault that in his instance was cured by ensuring the press stud type fixing was securely fitted. Failing that this thread might be of help where Mike @Skipton01 suggests a resolution. As I said at the beginning, scan results alway assist and might even avoid unnecessary purchases.

Kind regards,

Tom
Thank you Tom will have a read
 
You can deactivate the alarm system until you solve the problem. ;)
Check you coding for 46 module and RETRACT 10 from it. That will deactivate the alarm.
My coding was 06730 and 06720 deactivated the alarm. I have used this for a long period of time that the car was not used, to lower the battery consumption. The interior sensors alarm deactivation button light will be on all the time.
Amazing - will try that as an interim !
 
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Hi David,

It's a shame that this fault didn't manifest itself prior to the car being delivered to mine, as I'd have solved it for you quite easily.

2) Where is the offending sensor located and has anyone experienced the job of replacing it?
The glass break sensor is integrated into the tailgate and isn't easily replaced. As such, repairing it or disabling it are the two best options.

You can deactivate the alarm system until you solve the problem. ;)
Check you coding for 46 module and RETRACT 10 from it. That will deactivate the alarm.
My coding was 06730 and 06720 deactivated the alarm. I have used this for a long period of time that the car was not used, to lower the battery consumption. The interior sensors alarm deactivation button light will be on all the time.
Amazing - will try that as an interim !
This is a great suggestion and works perfectly for certain models of Central European A2, but you'll find that VCDS rejects the coding if you simply subtract 10 from the existing CCCU coding in your UK-spec A2. By being more brutal with the coding, it is possible to disable the alarm via VCDS, but you'll lose other functionality, too.

CDIS is, I'm sure handy, but it's diagnostics are not an equivalent of a VCDS or OBD Eleven scan, (other scan tools are available).
Is that so? How do you know? On what basis are you making this assertion?
It is true that VCDS is capable of doing more than the diagnostic tools of Colour DIS, but you seem to be implying that the Colour DIS diagnostic result cannot be trusted. Do you have any first-hand experience of using it, or indeed any solid, evidence-based reason for casting doubt upon its ability to successfully retrieve a fault code and the corresponding definition?

1) How do I disable the alarm temporarily until I can fix it properly - is there a fuse I could pull?
Alas, there is no fuse that you can pull. If the car was designed in this way, thieves would simply break into the car and immediately remove the appropriate fuse. The car is designed to make its theft difficult, which is great when everything is working nicely, but presents headaches when things go wrong.

It’s random in that it doesn’t always do it when I lock the car overnight, other times it will go off within a few minutes.
This behaviour is typical of the fault. I'd suggest that it's unlikely that the press-stud connection at the rear windscreen is the issue, but it's worth checking anyway. I'll send you a photo or two over WhatsApp to provide some further guidance.

Cheers,

Tom
 
Last edited:
Hi David,

It's a shame that this fault didn't manifest itself prior to the car being delivered to mine, as I'd have solved it for you quite easily.


The glass break sensor is integrated into the tailgate and isn't easily replaced. As such, repairing it or disabling it are the two best options.



This is a great suggestion and works perfectly for certain models of Central European A2, but you'll find that VCDS rejects the coding if you simply subtract 10 from the existing CCCU coding in your UK-spec A2. By being more brutal with the coding, it is possible to disable the alarm via VCDS, but you'll lose other functionality, too.


Is that so? How do you know? On what basis are you making this assertion?
It is true that VCDS is capable of doing more than the diagnostic tools of Colour DIS, but you seem to be impying that the Colour DIS diagnostic result cannot be trusted. Do you have any first-hand experience of using it, or indeed any solid, evidence-based reason for casting doubt upon its ability to successfully retrieve a fault code and the corresponding definition?


Alas, there is no fuse that you can pull. If the car was designed in this way, thieves would simply break into the car and immediately remove the appropriate fuse. The car is designed to make its theft difficult, which is great when everything is working nicely, but presents headaches when things go wrong.


This behaviour is typical of the fault. I'd suggest that it's unlikely that the press-stud connection at the rear windscreen is the issue, but it's worth checking anyway. I'll send you a photo or two over WhatsApp to provide some further guidance.

Cheers,

Tom
Thanks Tom
 
I've been having this exact same issue but my mechanic said locking my car with the key rather than the fob might be a workaround. It appeared to have been working... until today 😒
So many threads to read :oops:
 
I have tried that - but the alarm seems to auto-arm!
I've been having this exact same issue but my mechanic said locking my car with the key rather than the fob might be a workaround.
It suppose to re-alarm the car, but to me the random alarm doesn't come on anymore or very rarely.
Just try it, lock, unlock, then system auto-lock in 30s, then see if that changes anything, it worked for me.
Also @EWA2 scan the ccu for fault codes if you haven't yet, but this temporary work around I've mentioned above might work for you too.
 
OK removed the boot trim panel and the glass breakage sensor connection within and resecured, giving it a good wiggle in the progress. Seemed to be a good tight fit so probaby not the issue.

Anyway, here goes nothing: Ignition on, fault code cleared, ignition off then on again - no fault code (yet!).

Car now locked and behaving itself....
 
It suppose to re-alarm the car, but to me the random alarm doesn't come on anymore or very rarely.
Just try it, lock, unlock, then system auto-lock in 30s, then see if that changes anything, it worked for me.
Also @EWA2 scan the ccu for fault codes if you haven't yet, but this temporary work around I've mentioned above might work for you too.
Sorry I wasn't clear: I've tried it and it doesn't solve the issue.
 
"... you seem to be implying that the Colour DIS diagnostic result cannot be trusted. Do you have any first-hand experience of using it, or indeed any solid, evidence-based reason for casting doubt upon its ability to successfully retrieve a fault code and the corresponding definition?

My post, which read "CDIS is, I'm sure handy, but it's diagnostics are not an equivalent of a VCDS or OBD Eleven scan" was not intended to imply anything of the sort, and having read it again, I don't think it does. I'm sorry that you, and maybe other members have interpreted it as such.

The other Tom, @2work, had suggested, knowing the OP has VCDS, that he shared a VCDS scan report on here, as an overview of fault codes from all controllers will often hint that one fault is associated with, or a consequence of, another. I don't think such a shareable report file is possible with CDIS, If I'm wrong, again, I apologise.

Mac.
 
OK removed the boot trim panel and the glass breakage sensor connection within and resecured, giving it a good wiggle in the progress. Seemed to be a good tight fit so probaby not the issue.

Anyway, here goes nothing: Ignition on, fault code cleared, ignition off then on again - no fault code (yet!).

Car now locked and behaving itself....
Have you made any photo of the sensor in the progress?


Interesting fact @timmus. It definitelly works also on german A2s. There are also some other options to decode. This link will help to understand all the options. I hope the explanation is valid also for UK A2s:

This is a great suggestion and works perfectly for certain models of Central European A2, but you'll find that VCDS rejects the coding if you simply subtract 10 from the existing CCCU coding in your UK-spec A2. By being more brutal with the coding, it is possible to disable the alarm via VCDS, but you'll lose other functionality, too.
 
My post, which read "CDIS is, I'm sure handy, but it's diagnostics are not an equivalent of a VCDS or OBD Eleven scan" was not intended to imply anything of the sort, and having read it again, I don't think it does. I'm sorry that you, and maybe other members have interpreted it as such.

Mac.
Thanks for the clarification, Mac. I think we’ll declare this a misunderstanding. 👍🏻

Cheers,

Tom
 
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