Need help with random intermittent alarm - daily CLS

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May 11, 2018 | 07:45 PM
  #1  
Hi everyone. Had a 2006 CLS Designo (maroon/red interior) up until 2015 from 2007. It was a silver one that I sold.
I recently (about 7K miles ago) purchased another 2006 CLS as my daily driver.
It's a black on black with AMG package (exhaust + wheels) and it's been good.
But the one thing I'm at wits with is that the alarm for no apparent consistent reason, goes off. The parking lights blink/flash and the siren goes.
It stays going even after I jump in the car, start it and drive away. And it goes off in sequences/sets of 5. After 5 sets of going off for however long it goes (I haven't timed it), it'll stop. Usually until the next time I arm and/or disarm the car.
For a few weeks, it didn't do it anymore, but that also meant that when I armed/disarmed, the lights flashed, but there was no audio confirmation (which I'm fine with).
This is my daily driver and I even thought about just snipping off the wires to the actual siren...

I can't figure this one out. Don't know where to start looking and with an intermittent issue like this, bringing it into the dealer is asking for a massive bill.

Anyone have any ideas? Anything is greatly appreciated.
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May 12, 2018 | 10:17 AM
  #2  
Quote: Hi everyone. Had a 2006 CLS Designo (maroon/red interior) up until 2015 from 2007. It was a silver one that I sold.
I recently (about 7K miles ago) purchased another 2006 CLS as my daily driver.
It's a black on black with AMG package (exhaust + wheels) and it's been good.
But the one thing I'm at wits with is that the alarm for no apparent consistent reason, goes off. The parking lights blink/flash and the siren goes.
It stays going even after I jump in the car, start it and drive away. And it goes off in sequences/sets of 5. After 5 sets of going off for however long it goes (I haven't timed it), it'll stop. Usually until the next time I arm and/or disarm the car.
For a few weeks, it didn't do it anymore, but that also meant that when I armed/disarmed, the lights flashed, but there was no audio confirmation (which I'm fine with).
This is my daily driver and I even thought about just snipping off the wires to the actual siren...

I can't figure this one out. Don't know where to start looking and with an intermittent issue like this, bringing it into the dealer is asking for a massive bill.

Anyone have any ideas? Anything is greatly appreciated.
The chime on these cars is one of the silliest designs i've seen. They have an attached battery with a finite life and cannot be replaced, you have to change the whole chime unit. When they fail stuff like what you're experiencing tends to happen also you will notice low volume or no volume on the lock and unlock chirp sounds. I would start there as it is likely the case. It surprisingly isn't a massive bill, i think from the dealer a new one is around 150. Hopefully this is the issue and it isn't a deeper electrical issue. Also have you looked at the rear sam to see if any cables are loose or there's possibly a short somewhere.
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May 12, 2018 | 03:09 PM
  #3  
Check right side hood switch and siren unit. Common problem internal battery fails and/or circuit board corrodes requiring siren unit replacement. See attachments. BTW f8 @ rear SAM (located in trunk) is assigned to siren unit & left antenna therefore, do not recommend pulling fuse to silence alarm.



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May 15, 2018 | 03:34 AM
  #4  
Thank you both for this! Good start for me.
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