Urgent help with alarm

[steve333]

Hi all,my wife's r170 slk230 has developed a fault with the alarm,yesterday for the 1st time in 3 years ownership the alarm sounded whilst the car was locked and on the drive,after checking everything was ok locked the car and it was fine until about an hour ago when my wife got home from work parked and the the car when 30 minutes later the alarm went off but this time kept sounding after unlocking/locking again and the only way it would stop going off is to leave it unlocked with the drivers door slightly ajar,alarm was still going even with engine running,tried unlocking all doors/bonnet/boot the closing and locking with no effect(windows are fully up too)any ideas before one of our neighbours tries to strangle me

 

[grober]

SLK R170 Alarm Siren Location - Mercedes-Benz Owners' Forums
quite often its backup battteries or the siren itself

 

[steve333]

Many thanks for the link and quick reply Grober.

 

[steve333]

Does anyone know if disconnecting the car battery will stop the alarm going off(someone said on another forum the alarm has back up battery's?)

 

[grober]

The siren unit has backup batteries in it. If they corrode with age this can cause the alarm to sound off. You should be able to disconnect/remove the alarm unit . If it has internal damage from corrosion best to replace the entire unit--- around £100. Its a straight plug out/in

ps do a search for r170 alarm on the net- lots of info.

 

[steve333]

Many thanks Grober

 

[Abb]

As grober rightly says. I recently had this (well my father did) on his S class, removed the siren and replaced it with a new one from MB, circa £100 IIRC. Opened the old siren out of curiosity, and the internal battery had corroded and leaked allover the circuit board.
Been fine ever since.

 

[Auto-mobile]

How old is the slk? Early models alarm systems are not factory fit, main dealers fitted them as part of the pdi inspection, if that's the case you probably won't be able to buy an alarm siren anymore and it's probably best removing it.

Easy way to check is if you have interior motion sensors attached to the a pillars.

 

[steve333]

How old is the slk? Early models alarm systems are not factory fit, main dealers fitted them as part of the pdi inspection, if that's the case you probably won't be able to buy an alarm siren anymore and it's probably best removing it.

Easy way to check is if you have interior motion sensors attached to the a pillars.

It's a 2003/03,mrs decided to part x the car against a 2009 slk,made the dealer aware of the alarm issue,thanks for your reply.