Alarm going off

[fatscoleymo]

It happened twice through the night. Just unlocked and locked car and it switched off. 1st time I've had this. No obvious signs.

I'd done a VCDS scan a week or so ago and this was the only fault found:

 

Address 09: Cent. Elect. (J519)       Labels:. 1K0-937-08x-09.clb
   Part No SW: 1K0 937 087 R    HW: 1K0 937 087 R
   Component: BCM PQ35  H+  110 0651  
   Revision: 00110 AC    
   Coding: 46010AB8A85BF1C00010008031008164437000AE536D81605C8040200040
   Shop #: WSC 12047 008 00002
   VCID: 40D9436D5A87C73A4FB-8014

   Subsystem 1 - Part No: 3T2 955 119 A  Labels: 1KX-955-119.CLB
   Component: Wischer 05011  26  0602 
   Coding: 00D7B7

   Subsystem 2 - Part No: 1K0 955 559 AH  Labels: 1K0-955-559-AG.CLB
   Component: RLS 090112 05  54  0403 
   Coding: 2730ED

   Subsystem 3 - Part No: 7N0 951 171 A
   Component: DWA-Sensor 00  002 0206 

   Subsystem 4 - Part No: 1K8 951 605 B
   Component: LIN BACKUP HO  H11 9005 

1 Fault Found:
01134 - Alarm Horn (H12) 
            002 - Lower Limit Exceeded - Intermittent
             Freeze Frame:
                    Fault Status: 00100010
                    Fault Priority: 4
                    Fault Frequency: 3
                    Reset counter: 83
                    Mileage: 95669 km
                    Time Indication: 0
                    Date: 2018.03.28
                    Time: 10:36:19

             Freeze Frame:
                        Term 15 Off
                    Voltage: 14.35 V
                        OFF
                        ON
                        Term 50 Off
                        OFF
                        ON

 

It's the original alarm.

Has anybody any ideas what I should check for?

Thanks.

 

 

[fatscoleymo]

OK, found a few threads that seem to point to a low back up battery within the siren housing. I attempted to get to it this morning but foiled by a wiper arm reluctant to come off. Soaked in wd 40. Will try again tomorrow. A  New unit costs £200 + !!! Used one might be just as old, so battery swap looks favourite at moment.

Fats

[J.R.]

Assuming the old one has not leaked and destroyed the PCB finding a compatible battery will be your challenge, I think some smaller ones exist but may not have the same pin out.

 

I bought a cheap AliExpress one for my MK2 Octavia, it looked OK and may well have been a local market produced OEM unit (it had the VAG part number scratched out) but the vehicle could not establish comms with it so it was a waste of money.