Alarm system-self triggering - Activates erroneously.

[simon]

W202 DAS system- alarm triggers,at varying times after car vacated & locked & totally static.
Battery fully charged.
Zapper but not accidentally pressed.
Micro switch operation normal.

Before I get Star Diagnosis & apart from spider infiltration....are there any simple causes please Andy??

regards
Ernest

 

[fuzzer]

Alarm system-self triggering

Does it have the ultrasonics on the a pillars or the lasers on the b pillars?

 

[Anonymous]

Alarm system-self triggering

Have you got the motion sensor on your alarm?

 

[Anonymous]

Alarm system-self triggering

The motion sensors are very sensitive and I am reliably informed give the most trouble.

Will

 

[Anonymous]

Alarm system-self triggering

Thanks for your replies/interest.As Will says the system sensors are highly sensitive such that a spider or its web can trigger the system. I posted just in case there was a common/DIY solution.No reply from Andy suggests
there isnt.Star diagnosis & wallet out tomorrow.
regards
Simon

 

[DaveT]

Alarm system-self triggering

What happened about the alarm problem? I've just got the same symptoms; nothing done to provoke it. Any help would be appreciated....

DaveT
1996 C250TD

 

[Dave B]

Alarm system-self triggering

I've read this thread with interest....having the same car an'all.  Did anyone come up with a solution ?

This is probably totally useless, but, I had a similar problem with my other car whereby the alarm would keep going off for no reason.  I pinned it down to happening mainly on very cold nights - any other time of the day it was fine.  Eventually I turned down the sensitivity of the ultrasonics and the problem went away.....touch....Oh God, find me a piece of wood quick someone !

 

[DaveT]

Alarm system-self triggering

Just a thought; is the direction which the sensors look critical?  (Mine are mounted on bottom of the a-pillar- rectangular looking jobs with a little grill and led on them). One did get nudged, but I put it back, looking more or less parallel to the glass. The alarm is MB aftermarket(?)- the sensors look like the pics posted by Koolvin on the Benzsport forum.
Can the sensitivity be turned down? (I have no info on the system at all).
Can the system be isolated, so that I can at least lock the car?

Any clues would be much appreciated.

DaveT.

Funny it's three TD's innit?

 

[Anonymous]

Alarm system-self triggering

Sorry, there did not appear to be any interest.Star Diag.
revealed the motion sensor on my right B post had been  self triggering.These items are ultra sensitive, spiders can trigger them(reputedly by their body heat) & also their cobwebs have been known to be responsible. I have sprayed bug killer inside the car & area affected.
I am now on trial basis to ascertain if treatment was successful or if there is another cause.
New items cost 107-00 pounds + fitting + Vat. So if it starts playing up again I shall disable/switch off motion sensor.
regards
Ernest

 

[DaveT]

Alarm system-self triggering

Well now, I have solved my problem- but it won't help you. I had removed the boot plastic trim to get the bumper off and left it out overnight.   Result -
alarm problem.   Cause?  The boot light switch operates on the plastic trim panel, therefore no panel= lamp on permanently so alarm thinks boot is still open and lets you know.
Red face or what? (but it was nice to have worked it out).
  Now the B*****d EC won't switch off on the climate; needs gassing I guess- hope it's not the condenser leaking....

DaveT
(C250TD)

 

[Andy]

Alarm system-self triggering

Sorry Ernest,

I've been meaning to reply but need to get my facts straight.  But while I am doing that. The last problem we had similar to yours was an E class. 210. The problem caused by the central locking motor.

I will try and dig out the facts and come back to you.

Regards

Andy @ www.mercedesservicing.com

PS. There is no common fault with these alarms besides batteries. That I am aware of.

 

[Anonymous]

Alarm system-self triggering

Thanks Andy, kind of you. Its behaving itself at present- probably because I am de lousing the garage & extracting all known forms of insect life.Ron Dennis would be proud of me & might even smile!
regards
Ernest

 

[Anonymous]

Alarm system-self triggering

Just read your last post Dave T...its getting like the maternity ward here-one problem solved & another pops out!
regards
Ernest

 

[Stuart]

Alarm system-self triggering

All these problems i am seeing posted makes me glad i have not updated my current steed yet.I still think if you change the filters  etc on a diesel as per the owners manual
they will run for ever[well at least for a fair long while i hope]

 

[Andy]

Alarm system-self triggering

Hi Ernest

Feeding you incorrect info. The problem with the central locking pump. Was that it sent a feed to the interior light system thereby flatening the battery. Or when you went to the vehicle in the morning before you opened the vehicle the interior light was on.

The other problem with C classes we have had is to do with the siren. Its placed in the wing and catches water causing a problem. Ie going off intermittantly.

Regards

Andy @ www.mercedesservicing.com

 

[dave elcome]

Alarm system-self triggering

Ernest.

I have to say, you stand far more chance of curing your alarm problem, than getting Ron Denis to smile!!

 

[Anonymous]

Alarm system-self triggering

Hi Andy many thanks for that, will bear those points in mind for future ref. & will check the siren too for waterproofing!
regards
Ernest.

 

[Dave B]

Alarm system-self triggering

Andy:   Can you tell me which wing the siren is located under so I can check it out?  Is it easy to get at ??

Ernest:  did you eliminate your alarm problem ?

I've mysteriously encountered the same problem over the last week or so. Initially put it down to cats jumping onto the bonnet and roof in the early hours of the morning.  Not so sure now.   I expect the neighbours will be getting a bit miffed by now to say the least :shocked:

 

[rpalmeida]

Alarm system-self triggering

I had a similar problem on my 98 CLK (i.e same as a C class really!), where they replaced the central locking pump [under warranty at the time, thank God]. I was told that what was happening was that it was leaking air and the alarm thought a door had been opened.

It seems to me that the only way really to know is to use star diagnosis, or you could spend lots of time annoying your neighbours or lots of money on the wrong bits ...

 

[simon]

Alarm system-self triggering

Dave B. Yes thank you. Bug killer works a treat.