Alarm Triggering need help with whats causing it.

[QueenLizz]

Hello, I have a few faults with my 57 plate MK5 Golf GTI (UK SPEC) and I am wondering if anyone could help me. I did some research beforehand and got a friend to scan the car with VCDS. These are the following faults and modules. 

My biggest problem right now is the Alarm (at least I am assuming that's what it is). Basically, I lock the car and all is fine the doors are all locked no problem. I walk away from the car and some time later (its random could be 30mins later, 1h etc etc) the indicators will start to flash no alarm sound though. The doors all lock/unlock just fine but I can hear the second lock (deadlock/safelock) not coming on with the front passenger door if I put my ear close. We tried turning the interior monitoring sensitivity down and the tilt sensor sensitivity down already (both to 50%) but the cars indicators/alarm is still going off. The car is driving fine other than this.  It all started during the cold weather after opening/closing the bonnet due to checking if the O2 sensor wiring was faulty after the CEL came on because of it (the new sensor is getting installed this weekend the wires and fuses are fine)

I have also had the "alarm triggers" checked in the block data in cent. convenience. These show "12" across all 4 fields! I don't know what "12" is could anyone help? This would at least point me in the right direction of what could be wrong. I am thinking it's the alarm siren and shutting the bonnet somehow disturbed it. Or maybe it's the passenger door lock just getting worse but showing no symptoms? (the codes for that door have been there since owning the car and I have only just started to get this alarm issue)

Address 46: Central Conv.        Labels: 1K0-959-433-MAX (This has been a fault since I got the car)
Part No SW: 1K0 959 433 BT    HW: 1K0 959 433 BT

01134 - Alarm Horn (H12)
004 - No Signal/Communication - Intermittent

Address 52: Door Elect, Pass.        Labels: 1K0-959-702-MIN3 (Seems to be the second lock "deadlock" not engaging the door does lock/unlock and all windows work, heated mirror works.)
Part No SW: 1K0 959 702 M    HW: 1K0 959 702 M
Component: Tuer-SG         006 120B
Coding: 0000692
00097 - Front Passengers Central Locking (Safe) Motor (V162)
012 - Electrical Fault in Circuit
00929 - Locking Module for Central Locking; Front Passenger Side (F221)
008 - Implausible Signal

008753 - Oxygen (Lambda) Sensor B1 S1 (I have new one ready to be fitted this weekend)
P2231 - 004 - Signal Shorted to Heater Circuit


Thank you for your time, hope this makes sense.

[QueenLizz]

Managed to find an old log from a few months ago stored.

   Subsystem 1 - Part No: 1K0 951 605 D
   Component: LIN BACKUP HORN H07 9001

   Subsystem 2 - Part No: 1K0 951 178 A
   Component: Neigungssensor  003 0203

   Subsystem 3 - Part No: 1K0 951 178 A
   Component: Innenraumueberw.003 0203

Now displays today:

   Subsystem 1 - Component:   Sounder No Answer     

   Subsystem 2 - Part No: 1K0 951 178 A
   Component: Neigungssensor  003 0203

   Subsystem 3 - Part No: 1K0 951 178 A
   Component: Innenraumueberw.003 0203

When 1K0 951 605 D shows up the fault is "Intermittent" and when 1K0 951 605 D does not show up like now it does not show "Intermittent".

Anyway to disable the alarm going off until i can source a new one? Can i just unplug it and have no alarm / hazard flashing issue or disable it somehow in VCDS? 

Update:
So turns out the fuse box inside (drivers side) Fuse 17 (after Oct 2005) is the H12 Horn/Tilt sensor/Interior Monitoring sensor. So I yanked this out (fuse is fine). With the fuse still out and scanning with VCDS I now have 3 faults for the alarm system Interior Monitoring, Tilt Sensor and H12 Horn all not reachable (kinda to be expected since no fuse right!). My theory is with the fuse out its no longer "intermittent" but "permanent" now. So I'm guessing this means yeah the alarm is disabled and the other stuff but it wont randomly make connection and set the alarm off at say 2am in the morning? Someone correct me if I am wrong please, also this will stop battery drain also right (I read up the alarm being faulty can cause this).  It will be a week or so before I can get a new alarm anyway so if all is good and no annoying indicator/alarm starts flashing I will update to say so. At least this way others coming across this will have a solution or know pulling the fuse does not work). Fingers crossed!

[GreigC]

I use to have an X Reg 2000’ Audi S3 8L. One night the alarm kept randomly going off. Pressed the key fob to disarm it and thought no more of it as it stopped going off. The next night the alarm kept going off without fail I had to eventually leave the car unlocked all night manually using the lock on the drivers door.

After researching at the time it turned out inside the siren module there is a backup battery…. The battery leaks with age and corrodes the PCB board inside the alarm (sealed black box) this was causing all sorts of random errors and causing the alarm to go off. There was a revised part number that was shared across most VW & Audis. I replaced it.. around a 15min job plug and play the unit lived in the boot. Funnily enough when I got an Audi B5 S4 2000 X reg the same issue happened although the symptoms of the failure were slightly different…the hazards would only flash when alarm was set off - again a failed battery in the internal siren unit exactly the same part.

Also I would check on your cars DIS (the central display on your Speedo) - open each door, bonnet & boot individually and see if they show as open. The micro sensor in the latch may have failed/dirty triggering the alarm.

The problem you have maybe a similar issue?

[QueenLizz]

Good shout with the checking doors open i will do this when i next get to the car. I expect its the siren also and as you said failed backup battery. Seems the only ones online are used and old, from china (with a bad record for not working from a search) or they are like hens teeth and over £100. What i might do is get a used one with the same number as mine and swap it with mine. Then if it works fantastic if not open my old one and pray the battery has not leaked and damaged board and solder in a new one and seal it back up.

For now though so far "touch wood" the alarm has not gone off. I think pulling the fuse 17 and leaving it out was a good temp bodge for anyone reading this having the same issue. I have not tested for battery drain though it could well be draining my cars battery with fuse out but i don't think it would/should be able to. The light on drivers door still blinks as if the car is alarmed. I know its not as VCDS shows the alarm, tilt and interior monitoring not working (as no power to them i guess since the fuse being pulled cut the connection). I think at this point now the alarm will be relying on that backup battery since it cant connect to the big car battery. Only since the internal alarm battery is broke its not staying enabled (a good thing. I think if it was the alarm would still go off regardless of fuse).

[GreigC]

The siren is known for battery drain as the cars trying to recharge the internal leaking battery that’s failed but can’t communicate to say it’s charged as the boards completely fried with battery fluid.

If I had battery drain and was trying to diagnose… I’d disconnect the siren and test that for a few days it. (No harm doing this) it a bit awkward to access on the MK5 golf as it lives under the wheel arch but not the end of the world a YouTube guide will help you with this.

It’s a false economy to buy a 2nd hand siren as they have most likely failed or on the verge of failing most will be 10+ years old and definitely dont get a Chinese/copy unit. Buy genuine new.

I’m fairly sure if you close a door wrongly the car will lock all other doors and active the alarm and the red light for the immobiliser. (Could be wrong on that I’ll need to double check my car to confirm)

[QueenLizz]

Another update. It's been a while now with the fuse pulled. Alarm issues have gone (because there is no alarm). So outside of disabling it in software, it looks like yanking the fuse might help you if you ever face this issue of random alarm going off. I checked around online and its dead simple to replace the battery in these things and the alarm is very common on loads of cars. So i think what i will do now is go to the scrappy and pick up a few "duff" alarms and replace the battery in the best looking one (regardless if it works im replacing its battery as its going to be old anyway). Its only arch liner off, drill a rivet out, open box, solder battery in and then the reverse so a quick job anyway.