Thought I would start a new thread on this subject as I found not so much searching this forum and others across the net on this particular vehicle.

Here's the outline.

I have a 2001/2002 V8 4.0L

Over the past couple of nights I have been getting an alarm going off in my little cul de sac. Obviously, head out the window, who's is it that's keeping the neighbourhood up???
Turns out it was me!

I didn't know that my car had two alarm horns, or one horn and one siren to be exact.

With the siren going off there was no indication it was my car that was causing the trouble, no flashing indicators or anything.

But when it happened at 03:45 on the first morning and I walked outside in my dressing gown and slippers to investigate, it came as a bit of a surprise to find it was my cars siren going off. Not the normal horn alarm sound, but a siren sound.

No amount of pressing of the fob or turning of the key would shut the damn thing off, (it eventually shut itself off) so I sat here for hours scouring the sites for an answer.
Found stuff about boot/bonnet/door switches, low battery voltage, faulty ultrasonic sensors etc etc, but nothing conclusive.

Spent the afternoon checking all the said switches and sensors, checked the battery voltage, it was reading 12.13 volts after standing overnight, checked the alarm operation only to find I couldn't re-create the siren alarm.

I did find that the boot interior light was staying on dimly when the lid was shut, so thinking that may be causing a battery drain large enough to drop below the recommended voltage I disconnected it completely.
All that done and checked, and not finding anything else, I set the alarm at about 18:30 hrs and went inside.

Nothing happened with the alarm at all.....................until 03:05 in the morning

Then off it goes again. The neighbours are going to love me, two nights running..............

So this time I just went straight and dis-connected the main battery.
HA! That shut the damn thing up!
As soon as I did this, I also did a battery voltage check. Got the same reading as before, 12.13 volts, so the battery hasn't lost any more charge. Ruled that out then.
Back to bed.............

Up again and on the computer looking again, studying diagrams, found I had two "horns".
One PASSIVE SECURITY SOUNDER, one ACTIVE SECURITY SOUNDER, then found that they have distinctive sounds from each other.

Now we're getting somewhere.

Found the location of the passive sounder, related that to where my sound was coming from, seemed a logical answer, behind the front right headlight.
I also found that the passive sounder can be removed from the car with no adverse effects, i.e no fault lights on the dash, no screwing up the main alarm functions.

So today I have located and removed the passive sounder from my car.
Loads of pics to help along the way for anyone with the same problem.

The car has been double locked since 17:00hrs this afternoon, so far so good, no alarms, we will see how it goes overnight. If it happens again, then it's a good thrashing with a big branch. Hope nobody video's THAT.
"MADMAN IN BIRMINGHAM BEATS CAR IN SMALL HOURS OF THE MORNING WHILST IN DRESSING GOWN AND SLIPPERS"

Here we go then, how to remove the passive sounder.

The PASSIVE SOUNDER is located behind the right headlight, below the fuse box, and between the headlight and washer bottle.


To get to it you need to lift the fuse box out the way. If you have extra toys in your car you will have more wires in this part of the loom and it may be a little more difficult to move it out the way completely.
In my case there are 3 little plastic tangs to free the fuse box from it's holder and lift it up.

Two on the back edge


and one on the front



Then you can lift the board up and out the way.


Grab a light and have a look next to the washer bottle neck and you will see this, it has the word SOUNDER on the label. It is held in place with 2 bolts, both 10mm headed, the first one I have already removed, (don't bother with the other one on top that I already broke off, it's just a carrier for the cage.) The other bolt you need to remove is underneath the arch behind the liner and between the washer bottle and chassis.


Here's the other bolt you need to get to. You will need to give yourself extra access here, I removed the front wheel to get better access to the liner and bolt. Remove also the bolt in the washer bottle to allow it to be pulled down for better spannering.




Unplug the connection from the back of the sounder unit and move it out the way


So now it's unplugged and loose.
But you can't take it out yet.
It fouls on the plastic fuse box tray, so remove the three 10mm headed bolts that hold that in.




Et voila, NOW you can remove the sounder unit.



Clean the crap out from under the tray before you put everything back in.

Re-install the tray
Re-install the fuse box
Re-fit the bolt to the washer bottle under the arch
Re-fit the liner using new bolts and washers
Re-fit the front wheel
Enjoy your new siren free nights (hopefully)

I haven't had the car stand overnight so far as I only did this today, but as I've already said, there are no lights on the dash and the main alarm works as it should including the interior sensors and it drives normally.
So far there are no adverse effects that I can see or that have shown their faces.
I intend to have the sounder unit apart to check on the internal batteries status, I have a feeling that the cause of the alarm going off was because it was detecting it's own battery failure and dropping voltage rather than the cars main battery voltage.
I also have no idea as yet as to what functions this sounder serves and what it monitors through-out the car.
Maybe someone with more knowledge will come along and shed some light on the subject.
If this helps just one person it will be worth it.

I took a couple of sound bites so people could identify the different "horns"
if they are having the same problem.

 

The sound bites have disappeared, i'll try and put them in again

S Type NORMAL alarm sound.mp3

S Type Passive Siren alarm.mp3

 

At least there was no doubt what it was when you found it!

I'll add this to the how to thread.

 

Instead of "someone with more knowledge", would you settle for me?

I found this thread in the XK8 forum. Looks to be the same concept. Specifically, see post #11 for some of the logic:

https://www.jaguarforums.com/forum/x...ounder-149781/

The main gist is it's a somewhat independent alarm designed to protect the car if the main battery has been disconnected, taking out the "active" alarm.

I wonder if this may have been in reaction to an alarm issue on the Corvette around that time. Supposedly the car had a very hi-tech alarm, with a tilt sensor for towaway protection. The power source came from the main battery, protected by a position switch if the hood was opened. No way to disable the alarm, right? Enterprising thieves learned to drill through a specific spot on the fender, right into a battery cell. The electrolyte drained out and now the battery was dead, defeating the alarm. What ingenuity...

i looked for the "passive security sounder" in the S-type wiring diagrams. For all years, the table of contents said to see section 12.3. However, this section was entirely missing from 1999-2002. It was only present in the 2003+ wiring diagrams. No idea if it is the same as the earlier models. The 2003 diagram showed it was controlled directly by the General Electronic Control Module (GECM), but with no details of internal construction or activation logic:


JagRepair.com - Jaguar Repair Information Resource

Also, the 2003 diagram had a note saying some security features were only fitted in certain markets.

 

Hi Karl
I found DevonDavid's post with his problem on the passive sounder during my early morning searches the first morning this happened, different car (XK8) but same symptoms/problem/solution.
I also dug around in the S-Type electrical diagrams and found that fig 12.3 and 12.4 were missing from the files, both security information, which I concluded was deliberate due to potential mis-use of them.
Then, as you have, I also found the 2003 diagrams which does show them.
I've since found that there were two different types of passive sounder; a "normal" one and and "intelligent" one.
Please don't ask me what the difference is, I don't know, haven't got that far yet.
The only thing I can report so far is that my car did not alarm at all last night, and that is all that currently matters. My neighbours slept soundly thank god.
You are probably quite right with it being a back-up alarm system, but given today's ingenious or blatant thieves, if they want it bad enough, they'll have it. And it's insured, and I can always buy another.
I just thinking now, if the passive alarm has it's own back-up batteries, I wonder if the active one does too..................and if not can I change it for one that does................
See what you've done now, made me do a left turn, I'm going to have to investigate now.

 

Hi Stevep10,
I am a new member, and came across your article, when following a thread.
I too have been having the auxiliary alarm going off intermittently on my 2.7 ltr 57 plate S Type. I took advice from the local Jaguar agents who said I could remove the device without affecting the operation of the car. However you need to remove it and destroy it because once it's disconnected the alarm will be triggered. So I was very interested in you comprehensive article on how to remove it. However, when I tried to follow your instructions and pictures, I found that the fuse box could not be removed, or lifted to one side, because it is held tightly in place by the two cable harnesses at the bottom. There is just not enough slack available to move the fuse box to see, never mind get access to the alarm. Just wondered how you overcame this problem. It maybe that your car was an earlier model and the wiring loom was different. Any advise would be most welcome.

 

The 2.7D is different in many many ways.

Also, not sold in USA where most members are.

You may do better starting a new thread, also in a UK/Europe forum.

 

Hi JagV8,
Thank you for the reply and advice. I'll start a new thread.

 

Bump to an older thread:

When you unplugged the passive sounder, did it start screaming? The reason I ask is the full removal looks to be quite the chore. Perhaps the next victim could be spared a lot of trouble if they simply unplugged the sounder versus removing it. If the sounder itself isn't making any noise, and the rest of the car is behaving itself with the sounder unplugged, it seems you could just leave it there.

However, note post #6. In that instance, the sounder itself was making noise as soon as it was unplugged. Perhaps different versions were installed in different markets, but that's just a guess.

 

Hi Karl
My sounder didn't even squeak when I unplugged it. I have read that some people, especially dealers just unplug it and leave it in place, certainly the quicker option, with me it was curiosity as well as a cure,
I did end up opening up the unit, found corroded and leaked batteries inside. Car has had no reoccurance of the alarms going off since.