C240 Alarm (with it's own mind!)

[Angri]

Hi there, just joined (so be patient with me please . . . !)

Have c240 - 1999, never had any problems 'til about five months ago - and whenever I parked car in a sunny spot (too few of those I fear!) the damned alarm would set itself off.

. . and I would have to unlock it!

This now happens more frequently (and also at any temperature!) . . I've asked my local MB dealership (AKA Useless wazzocks) and they provided the normal "hurrumpgh herrgh - er - - leavit with us for a few days - (together with your credit card and deeds to your house) and we'll see what we can find . . . !

Deciding not to bankrupt myself with their vagueness - - I thought I'd ask the experts . . . so! does anyone at the MBClub know of a similar problem please . . and how should I go about fixing it please?

Many thanks

Angrier :bannana:

 

[reflexboy]

Hi Angri- Not sure if you have the same type of ultra sonic sensors as me, but pre-face lift cars were fitted with sensors at the bottom of the windscreen pillars. These were over sensitive and caused the alarm to give false triggers. Being a later, facelift model, Im not sure if you have the same sensors. I believe the facelift models had the sensors fitted at the top of the door pillars. Worth checking mate.

 

[R2D2]

This will sound silly, but close your air vents when you lock up the car!

 

[mobeyone]

what about turning the sensitivity down? I think on my 202 had a small black box under the driveres seat which allowed me to turn this down??

 

[C240Sport97]

C240's were post face lift only, and the sensors are on the B pillar if the alarm is factory fit

Hi Angri- Not sure if you have the same type of ultra sonic sensors as me, but pre-face lift cars were fitted with sensors at the bottom of the windscreen pillars. These were over sensitive and caused the alarm to give false triggers. Being a later, facelift model, Im not sure if you have the same sensors. I believe the facelift models had the sensors fitted at the top of the door pillars. Worth checking mate.

 

[Shude]

Try turning the internal sensors off by pressing the button the dash. If this stops the alarm going off then you know it's something to do with the interior or the sensors. If the alarm still goes off then it's something else. There's nothing like applying some logic to a problem!

 

[Alex Argent]

The interior movement sensors will definitely be at the top of the door pillars. IIRC, all W202 V6's (C240 & C280) had the factory alarm fitted as standard.

I had the same problem occur a few days after first getting my C240 about 2 years back. The sensors are really, REALLY sensitive and the culprit setting mine off for three consecutive nights at between 12.00am to 3.00am ( ) was a really tiny spider I found taking a walk on the dash one morning! Since disposing of him (or her - I didn't look that closely), the problem went away. Fortunately, my neighbours were very understanding

As R2D2 says, closing the air vents may help. The slightest air movement in the locked car may be causing something to move slightly, setting the alarm off. To test the sensitivity, lock the car in the normal way leaving one of the windows open a couple of inches. Wait about 30 seconds for the alarm to arm itself then slowly stick a finger in the opening and wiggle it about. I don't even need to wiggle my finger - the alarm has triggered before I even get that far!

One way to reduce the sensitivity is to carefully place some clear sticky tape over the interior sensors. I am fairly certain there's no user adjustment other than completely taking them off line (as Shude says, press relevant dash switch before locking car. However I'd consider this a temporary/test measure only because what's then the point of having the car alarmed in the first place?). Also, in the summer months I tend to carry a can of insect spray in the car and give it a quick squirt before locking. Maybe not as nice as "Feu a l'Orange", but extremely effective

Good luck in sorting it.

Alex

 

[Angri]

Alarm prob's . .

Well, I'd like to thank everyone whom has taken time out to help me with the problem . . . .
Reflexboy, R2D2, Mobeyone, C240Sport97 (I wonder what model he owns???), Shude, and Alex Argent . .

I think it's fair to say that in a matter of days I have learned of knowledge that would otherwise have taken me many months of detective work, and much hair pulling (not that there's much left - I know winter's coming before most folks do!!).

So - sincere thanks to all the above guys . . I'll employ your suggestions - let you know how it develops, (and if I learn anything else along the way!!!)

So take care, and cheeripips for now!

Angri

 

[fuzzer]

ill put money on your battery being on its road out. when the voltage drops it sets the alarm off. My c240 suffered from this too.

 

[High-Lo]

C240Sport97 (I wonder what model he owns???)

You may not believe it Angri but I do believe C240Sport97 owns a CLK55 AMG