X150 alarm sounder query.

[garagedood]

Hi all.
Just occasionally my 2008 x150 will sound the alarm without any apparent cause.
I have ruled out several potential causes including the neighbours cat.
I have very recently replaced the original vehicle battery with a Bosch S4 so am happy that a failing battery is not the cause.
Last night it went off at 02:30 hrs for no apparent reason. No sign of any external cause and as the car is connected to its 'Jaguar' branded battery maintainer some mystery drop in voltage could not be to blame.
My suspicion is turning to the alarm sounder unit. It does not look too difficult to get after a little dismantling but what will I find when I get it out?
Does anyone know if the unit is self powered and if so are the batteries easy to get at?
Looking at some images on eBay and google it does not look to me that it will come apart, maybe someone here knows better!
I am quite handy with a soldering iron so replacing the rechargeable batteries if there are any and can be obtained should not be too much of a problem providing it comes apart.
Any advice appreciated.Cheers!.

[mike020150]

I confess I have not had cause to examine the sounders on my X150s and no-one else has contacted me about theirs. The units appear to be both more reliable and different from those used on earlier models which certainly did have rechargeable batteries inside. You could be on a voyage of discovery. The answers to your queries would be very useful for us all to know! Mike.

[garagedood]

Thanks Mike.I just remembered that I had obtained ( from eBay on a cd rom ) a workshop manual for the X150 some time ago. I have other cars - the MGB has been taking a lot of my time lately - so just forgot I had it!
The manual is pretty impressive for the few pounds I paid for it. More than £5 but less than £10 I think, can't remember exactly.
It runs to 4000 pages and looks very ' official' .
Anyhow I have have dug it out and have discovered from this that the sounder is indeed self powered and is referred to as the " battery backed sounder" .
There are nice clear instructions on how to remove and replace the sounder ( it is underneath the right side pedestrian protection unit - the 'squib' that raises the bonnet in a collision which has to be removed ) but nothing about changing the batteries within.
it looks to me that the same sounder unit is also used in some of the Jaguars 'cousins' eg, Ford,Land Rover, Mazda and even late model Volvo ones look similar.
A unit from a breaking 2013 Focus is on its way to me ( eBay £17 delivered) that I will dismantle to see what lies within.
In the meantime I will be using the XK regularly for the next couple of weeks so will get the chance to run the car with the heat on high for a while which just might exterminate anything ( eg spiders) that might have taken up residence in the vents!
The unwanted alarm activations are so rare and random that I guess it is just possible that this is the cause.
I know through personal experience that they can set off house alarms by crawling over and in to sensors.

[mike020150]

Good luck investigating the eBay unit. I hope it proves a successful route to a solution and I look forward to your postings about it. Mike.

[garagedood]

The sounder arrived,actually from a 2015 Focus not 2013 as I said earlier.
It is a plastic sounder unit contained in a metal outer case.
The plastic case has the makers name ' Delphi' on it below a code number, PA66-GF30, ignore this number as it refers to the type of plastic the case is made of and not an identifier for the sounder.These Delphi units are ubiquitous and seem to fitted in everything from Audi to Zastava, if they still make them!
The metal case is held together by protrusions on the back half poking through slots in the front which are stamped to form a sort of rivet.
These can easily be ground flat with a Dremel type tool to allow the two halves of the metal outer to be prized apart.
This reveals the plastic sounder which can then be prized carefully from the back half
The plastic sounder inside seems to be heat bonded but comes apart quite easily. I placed it in the vice and applied pressure along the longest edges and it came away enough to allow it to be prized open without damage.
This revealed the back of the sounder horn, a PCB and a battery pack.
The horn and the battery pack are connected to the PCB by plugs so can easily be detached.
The battery is a wrapped twin AAA NiMH rechargeable type, 2.4v , 550mAh. ( marked 55AAAH2BMX)
This type of battery is widely available used in DECT phones, baby monitors etc.
There are many plug shapes in use for different devices so it is possible that is may be necessary to snip off the leads and solder the correct plug to the new battery. Soldering wires together is a lot easier than trying to solder on to battery ends! Observing correct polarity of course,don't just trust the wire colours.
You could glue the plastic back together once the new battery is in but putting it in the metal case would probably be enough to hold it together as it fits together quite snugly.
There is tons of space in the interior to allow the metal case to be drilled and self tappers used to hold it together if necessary as we have ground off the rivet heads.
Anyway to answer my own question;
Yes the sounder is self powered.
No it is not difficult to change the battery.
Yes the batteries are available.
Seems to me that it is a simple enough job for someone to do with basic tools and skills once the unit is out if the car.
However I am not absolutely certain yet that the sounder is the problem.
The alarm never went off while it was laid up over the winter and as a summer day car it is rarely used unless I can get the top down. This means that on a nice day it would be easy for a squatter in the shape if a spider, fly or moth to become trapped in it when the car is closed up.
This said rechargeable batteries do not last forever and as my XK is nearly 8yo the sounder battery might be past it and should probably be replaced anyway.
What I do not know is whether or not a dud sounder battery can actually trigger the main alarm to sound.
I have emailed Delphi ( the makers name found on the plastic internal case) but won't hold my breath for an answer.
Someone reading this thread might know.
I can send pics to anyone interested by email but unfortunately have been unable to upload them to the site from my iPad - files are too big it seems.

[mike020150]

Excellent work! I'm sure your experience will give everyone the necessary confidence to open up ageing sounders when they become unreliable. Why the batteries aren't replaceable as a normal service item remains a mystery (I'm trying not to appear cynical). Mike.

[garagedood]

Well I pulled the BBS out of the XK today and opened it up.
The bad news is that the battery inside has pins ( I think 5? , 3x+ve and 2x -ve.) soldered directly to the PCB and is 6 volts not 2.4 like the one from the Focus, perhaps because of the tilt sensor.
It would be possible to de- solder and solder in a new battery but it would need more skill I think than would be needed for the smaller one.
The good news is that the innards appear to be in perfect condition with no corrosion or battery leak crud to be seen.
The battery voltage is a little over the 6 volts so as far as I can tell is in perfect order.
This of course means that I still do not know what is setting the alarm off.
I'm coming back round to the notion of some sort of creepy crawly perhaps being the culprit.

The part number on the BBS is 6G9N - 19G229 - DE if anyone is interested.

[mike020150]

Thanks for keeping us all posted. I suppose you have answered my question on why the battery isn't a service replacement item. Jaguar saved the cost of a connector! Mike.

[PTR200Jag]

Perhaps you can leave the sounder disconnected for a while? And see how it goes with the false alarms?
Having disconnected my sounder, see other thread, I have no issues as yet, although on x100 maybe the 150 is the same?
This would enable you to confirm it's not the sounder.

[garagedood]

Could be worth a try I suppose.
Not sure what the missing voltage would mean to the rest of the system though.
The car has its cover on and connected to the bat maintainer now as we are going away for a couple of weeks on a caravan trip.
In the meantime the Mrs brought me some slow release bug killing stuff when she went shopping that I have left in the car (after making sure that it would not be harmful to leather etc.) although all I have seen is a couple of random aphids, no cobwebs or anything.
The activations are so rare and infrequent that I now think it unlikely that it is any kind of fault with the car.
I would have thought there would be at least some predictability to them if there were a fault present.
Funnily enough my next door neighbour has had an identical problem with his Skoda Yeti.
Neither car has sounded off for a couple of weeks now.
This XK is a long term keeper ( had it fours years and no plan to change it) so I might invest in a tool that can diagnose the alarm if it keeps happening.
I am sure I will get an update from the neighbours when I get back in a couple of weeks if it has been going off again.

[garagedood]

After having the car scanned at a local Jaguar specialist with IDS/SDS and codes cleared all seems well now.
Fingers crossed that is the end of the story.