just got car back from dealers, while it is just sitting outside my house the alarm goes off for no reason.
Its not the main alarm that sounds the horns and flashes the lights.
The dealer says its a secondary alarm, that is a loud repeating beeping noise, seperate to the main alarm, comes on for about 20 beeps then rests and starts over.
The dealer says is a secondary back up alarm that sounds when the electrics/electronics are messed with, it just happens that the car was in for a ECM yesterday.
the dealer says (over the phone) that it always happens and needs a short connection loom between the sounder and main loom replaced.

Could it me that the battery is pretty low because of the failer and non start connected to the ECM (battery was disconnected) and that is fireing off the alarm??

How do you turn the secondary alarm off??? see below

just a clue, but I think one set of keys turns it off and the other does not?? need to double check that when it decides to go off again, but maybe the keys got mixed up,
Well can I confirm that only 1 key turns it off, but at least I can turn it off.
but it still goes off about every 15mins

I love my jag, but it loves the bank manager more than me, seems to me that a good mod would be to the SatNav to include Banks and ATM machines

stan

 

Where can I find out information on the passive alarm.

please see below, when the passive alarm goes off, one key will switch it off the other will not, both keys work the main central door lock, on off but only one will stop the passive alarm.
can anyone suggest why the passive alarm is going off, does the passive system read battery voltage?
Is there a way to reset the passive system or configure it? without taking out a mortgage at the dealers.
Also where can I find instructions to remove the fuse box to obtain access to the sounder unit.
going to play with it today so any suggestions.

Stan

 

Stan, I've moved this thread to the S type section where you should get more results

 

Well there is no secondary alarm so we are at a standstill already??

Are you saying the horn is blowing or what is beeping? We can't tell whats going on without the proper terms being used.

Did the dealer replace the ECM? I can't tell what happened?? His explanation of a wiring loom makes no sense at all.
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The secondary alarm is referred to as a passive system.
The main alarm is an intrusion device, operated by switches and proximity devices in the cabin. When activated it will sound the horns and flash the lights.
The passive system appears to work on voltage fluctuation and has a separate sounder unit, situated under the bonnet/hood below the fuse box and when activated by a current drop admits a loud series of beeps.
I understand that the passive alarm was a factory extra and is independent of the cars battery.
The loom/wires in question connects the sounder to the main loom, and it seems that failure of this part is due to corrosion and is a known documented fault.
In my case, the battery was disconnected and the ECM replaced and the fault started directly after that.
Although I have not found a direct cause, since taking the car on its first run since the ECM change the passive/secondary alarm has stayed silent.
I am wondering if a low battery may have been the problem???
In any event at the moment its silent.

Stan

 

There's a backup battery for that alarm. Don't know if it's rechargeable but I guess it must be. They can fail and I've seen threads (I think on UK forum) about disconnecting it (the sounder, I suspect), kinda painful to get to.

I do think low (main) battery could be the cause. Modern cars need a good power supply.

 

Well it seems my hunch and the members advice was correct, since giving the car a run to charge the battery, the alarm has not activated by itself, on the 3rd day now so fingers crossed!!

On to the next challenge!!!!
thanks to everyone.

Stan

 

JagV8,
Your diagnose was spot on, since the car had a good run and battery was charged no more Beep-Beep-Beep thanks for the input from me and my neighbors.
I could have torn the loom apart on what the dealer said.
Stan

 

Hooray - and what a relief you didn't tear into the loom!

 

Just done a 250mile round trip.
Parked outside the hotel and after about 4 hours the passive alarm started to sound, then it resets and sounds again, after a while it stopped for a few hours and then started the cycle all over again.
I thought it had fixed itself as I had no problems for a week, now the beep-beep-beep is back.
I checked out the wiring diagram, and it shows the passive transmitter, the front control module and the sound unit connections.
I can’t really find out what the passive unit does, and why would you want a secondary unit, that is not as loud as the main alarm?

I can find out where or how the passive alarm picks up the activation signal or what activates it, any why it would sound intermittently sometime within seconds other within weeks??
And how it is switched on and off, because at one time it was sounding and I couldn’t switch it off from the key.
To try and do some investigative tests I need at least to know the theory of operation, so any help would be appreciated.
Stan

 

It's anti-theft.

 

Yes but how does it operate, it appears to be issolated from the main intrusion alarm?
where are the sensors ? does it have internal battery back-up
On the wiring I see a transmitter/reciever? for the passive alarm,
comes on for no reason at all sometimes hours after car last used.
how do you turn it off?
somtimes it turns off from remote key others it wont turn off,
can stays off for several days then resets and comes on evey minute or so.
driving me nuts.
has it got a fuse?
seems to be under the RH front fuse box, how do you remove that fuse box to get to it, just want to unplug the sounder if I can get to it

stan

 

Sadly, I think what you need to solve is "what is wrong?" as yours is not working as intended (I expect you can glean most of the intended workings from JTIS). I suppose you could go around measuring things to cross-check but I think you'll need lots of time and good electrical skills...

 

Hi Stan,
Did you eventually find a working solution to your problem? I have exactly the same problem on my X308. It started after a longer disconnection of the battery and is probably associated with a low battery as I have an idle current take-off there (which I also haven't solved yet).

 

Wrong forum as the cars are so different.

 

I recently fitted a new battery and from the moment I disconnected the old one until I connected the new, I got exactly this secondary alarm sound. I guess it is to stop thieves disconnecting the battery to defeat the main alarm. So if yours is operating when it shouldn't, the wiring has to be a possible culprit. If the secondary alarm things the main power is disconnected it will operate as you describe. Could be the unit itself I suppose...

 

I set a new thread on the sounds of the passive alarm against the sound of the proper alarm. They are 2 completely different sounds. One sounds like a siren, the other is obviously the cars own horn.


As already said, the passive alarm is located under the fuse box, I posted a thread on it's removal as well. Its not difficult to remove, most people just un-plug it and leave it.
The passive alarm has internal rechargeable batteries that do fail eventually, and when they start to fail, the siren goes off because it detects the drop in the voltage of the batteries and not of the cars voltage.
Kind of a vicious circle, the siren is detecting it's own failure.


Here's the link to the passive sounder removal
https://www.jaguarforums.com/forum/s...02-how-189612/


If you look post #2 it has the sound bites on there for you to tell the difference between the two alarms.