W209 Alarm Constantly Going Off

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KillerHERTZ

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SL63 AMG
For the past week every time I return to my car the indicators are flashing and the alarm has gone off. For the past 2 nights I have had to go out at 4am to turn it off.

Reading up, the W209 is meant to use an ultrasonic system which can be effected by metallic objects in the car, I have removed everything including items from the armrest to no avail.

The only thing which appears to work is if I manually disable the internal motion sensor.

Any ideas? maybe even removing the sensor and cleaning it from dust etc?
 
Its probably the siren gone faulty. Ours was exactly the same. Pretty common issue allegedly.
 
Happens to me every summer and it's normally a spider making webs over the alarm sensors!
 
Its probably the siren gone faulty. Ours was exactly the same. Pretty common issue allegedly.

If its the siren only, surely the indicators wouldnt flash?

Happens to me every summer and it's normally a spider making webs over the alarm sensors!

Also happened to me with the W202, this however its within minutes of locking the car any time of day...
 
Probably the siren at fault mate, a Star short test will confirm and will be logged in the Rear Sam. May need a new multiplug to the siren aswell, as these get wet and go green :thumb:
 
They do flash if the siren is faulty. Sometimes in a very odd fast sequence.
 
Yes had the same fault on the CL a couple of weeks ago. New siren, £70.00
 
Just got home from the pub with the car in Christmas-tree-tronic and a 'polite but firm' note from a neighbour basically asking me to sort it out... :( this was after me deactivating the motion sensor aswell.
 
Unplugging the alarm siren may prove the siren is at fault… if the hazards stop flashing, remember, you are never more than a mile from a faulty siren.

Dec
 
Part arrived today - thanks Jay.

Where on earth is the Alarm Siren? I have spend 2 hours removing both front wheels, wheel arch liners to no avail.

Its meant to be in the nearside front arch but all I could find was the cars horn which looks totally different...!

Looking at photos of a W203 WIS, it looks like its behind a cage...
 
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Have a look up in the wiper motor neck of the woods. Some SLKs have them up there.

I'm probably wrong but worth a look at least.
 
Couple of photos:

Nearside:

arch0.jpg


Offside:

arch1.jpg
 
On ours it was in the nearside wheelarch behind the front wheel.
 
Typical! I didnt think there was any space there :(
 
Fitted the new alarm, touchwood it has solved the problem!

The car seems to have the netherlands setting now however - beeps when you lock it and unlock it. - doesnt bother me though, I like it!

As I had the battery disconnected for so long, the car thinks it needs a service, I need to reset it any ideas? I tried the PDF from Mercedes posted a couple of weeks ago which hasnt worked.
 

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