I wonder If somebody can please offer any advice on the following issue/s please.

 

I have a 2008 mark 2 Fabia 3 estate and for the last few weeks, the alarm has been going frequently off at random times.  I have also noted that the doors sometimes lock themselves, and often  go in to a cycle of repeatedly locking and unlocking.  This happens regardless of whether or not the keys are in the ignition, and even when I'm driving.  I have noted however that when the keys are in the ignition, it only appears to be the drivers door actuator which repeatedly cycles, but if I take the keys out of the ignition, I can also hear the other doors joining in. The front courtesy light is set to the off position, but I have noted that when stationary, the rear courtesy light will come on when the car decides to lock itself and arm the alarm - I have not noticed this while driving, but the red alarm led on the driver's door does illuminate intermittently with each cycling of the door actuator.

 

So far, I have replaced the driver's door wiring harness, as this was visibly damaged and had been repaired previously.  I have also replaced the driver's door actuator, but he problem still persists.  I am currently being forced to leave the car at home with the battery disconnected and would welcome any suggestions please.

 

Many thanks in advance

You have checked the replacement wires were not damaged, I assume? (New, not used).

Also, its always worth checking the passenger side too, as they are also likely to snap/sever.

Check the obvious things, such as fuses, battery condition, etc. They hate weak batteries and any loose connections. Even if the relevant fuses LOOk ok, try switching them for new ones anyway and pinch the terminal close so as to be a tight fit, if possible.

Check there is no water ingress into the electrical components in the door, in the roof lining, under the bonnet, etc. 

I do vaguely remember alarm issues on certain occasions/models but can't remember what they were. (No alarm on mine). 

Check all this sort of stuff as its not gonna cost to look but could cost plenty to overlook!

 

You might need to get someone with the VCDS equipment, to help look at any coded faults, if you can find someone local.

Edited 6 January, 20215 yr by mrgf

Thank you mrgf.

 

The wiring harness was a new genuine part and appeared good prior to installation.

 

I have just checked the battery voltage and it is good at 12.9v.

 

I also had a quick look at the passenger side door loom (under the rubber bellows between the door and the A frame) and it looks as good as new.

There is no evidence of water ingress under the bonnet or around the front doors, but I do have a slightly damp rear off-side footwell, so that may be worth investigating.

 

I will check and replace the relevant fuse/fuses when daylight and work allows.

 

After checking the passenger door loom and giving all of the doors a good slam, I took the car out for a run, but the doors started locking and unlocking repeatedly once again after only half a mile; each time flashing the hazards as you would expect when you arm or disarm the alarm. The driver's doors must have cycled 100 times during that short trip not sure about the others).

 

To rule out a faulty key fob, I used my spare key this time (leaving my main key at home), but this made no difference.

 

I have noted that my bonnet release cable is not operating correctly and the bonnet will not close properly unless the bonnet release lever is pushed home first.  While I know this will need to be remedied by either lubricating or replacing, I have begun to wonder if there is a sensor for the bonnet release which may be affected by this, or whether this is a red herring.

 

The alarm sounded again while I was trying to disconnect the battery after returning home.  the locks were cycling at the time and it went off again after disconnecting the battery.  I'm assuming that I must have disconnected it while the alarm was activated, but the locks were cycling so fast at that point that it was difficult to know whether the alarm was active or not at the point at which I pulled the battery cable off - it has however been quiet for half an hour now, so I'm hoping for the sake of my neighbours that it stays that way.

F II Alarm .pdfF II Central locking.pdf

 

If you have not done it, it would also help to check for fault codes with a code reader.

I have attached PDFs for the alarm and central locking. In both alarm and central locking the BCM - J519 - and the convenience module - J393 - have lots of connections and you could have a fault in the controllers.

Thank you. That's very kind of you  26DIPP.

I do not have the equipment to check for fault codes, but am beginning  to think that I'll just have to book the car in to a garage.

There may well be an issue with the bonnet release as I think some models had a dash warning issue if the bonnet was ajar and also, it may affect the operation of the wipers and possibly the alarm, due to it 'thinking" there is an intrusion... 

I would get that sorted and see how it goes but I have no idea if the system would operate from the pull handle or-more likely, the actual mechanism at the bonnet lock/catch. I think its ok to spray all that area with something akin to WD40 and then grease it up unless someone tells you otherwise so try to be sure first. I say this as I found out to my downcast, spraying/cleaning the REAR boot pop, can make the mechanism go into spasms and ruin it, making it necessary to replace the electronic unit, at around £30 a-well, pop! 

Many thanks mrgf

Update and Hopefully a Fix:

 

I've just picked up my Fabia from the garage where it has been for the last 6 weeks and they think that they have fixed the problem 

 

Having initially replaced the bonnet release cable (it was knackered) and the bonnet lock and microswitch (also showing some damage to the wiring), the fault was still apparent. 

 

Despite me having already changed the driver's door lock/actuator with a cheap aftermarket unit, their diagnostic software still indicated a fault on the same so they ordered a genuine VAG lock/actuator and this seems to have fixed the issue.  

 

Only time will tell, but at this point, the lesson to be learned is to avoid cheap aftermarket lock/actuator units.  

 

I hope that my presumed fix is not premature and that this post may be useful to someone else in the future.

 

Many thanks once again to all of those who provided me with advice and assistance, it really is much appreciated.