C-Class (W203) 2001-2007, C160, C180, C200, C220, C230, C240, C270, C280, C300, C320, C230K, C350, Coupe

Random alarm and blinking lights on C240

Old Jun 7, 2009 | 12:18 AM
  #1  
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C240
Random alarm and blinking lights on C240

My '05 C240 is randomly sounding the alarm. This happens several times per day. I can be in the house and it goes off....

Also, I have noticed that sometimes (just after locking it) that the flashers keep blinking (non-stop). The flasher button is not pressed.

I have also had the battery go dead (one time). I think that this was from the flashers going all night.

I've read other posts that make me think I may need a new "trip sensor". Is this causing the alarm to go off (for no reason)?

A friend said that the alarm could be going off because the battery is low.

Maybe the battery is going low because of the "seat control modules" (as I've read in other posts). Still I think that it went dead (that one time) because the "flasher issue" (as mentioned above).

When the alarm goes off, it can't always be stopped with the SmartKey.

If I could find the correct fuse to turn the alarm off I'd be happy. All 3 fuse areas have no "fuse map".... So I don't know what one controls the alarm.

It seems to me that I've got a serious electrical issue.

Any input is appreciated.
Thanks
David
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Old Jun 7, 2009 | 01:17 AM
  #2  
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RLE
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Originally Posted by englsprogeny
My '05 C240 is randomly sounding the alarm. This happens several times per day. I can be in the house and it goes off....

Also, I have noticed that sometimes (just after locking it) that the flashers keep blinking (non-stop). The flasher button is not pressed.

I have also had the battery go dead (one time). I think that this was from the flashers going all night.

I've read other posts that make me think I may need a new "trip sensor". Is this causing the alarm to go off (for no reason)?

A friend said that the alarm could be going off because the battery is low.

Maybe the battery is going low because of the "seat control modules" (as I've read in other posts). Still I think that it went dead (that one time) because the "flasher issue" (as mentioned above).

When the alarm goes off, it can't always be stopped with the SmartKey.

If I could find the correct fuse to turn the alarm off I'd be happy. All 3 fuse areas have no "fuse map".... So I don't know what one controls the alarm.

It seems to me that I've got a serious electrical issue.

Any input is appreciated.
Thanks
David
Ah, yes, I remember all this crap when I had my W203. Thank God it's gone.

The fuse paper should be in a holder in the fuse box on the left end of the dash, folded into a one inch square.
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Old Jun 7, 2009 | 06:49 AM
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From: Llandudno, Cape Town, South Africa
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Old Jun 7, 2009 | 06:50 AM
  #4  
Glyn M Ruck's Avatar
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
BTW - you are on the wrong forum
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Old Jun 7, 2009 | 12:04 PM
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2005 c230k
This may not be your issue but I have had your problem ever since I owned my car for 4 years and it is was always the alarm horn in my case. I have had the horn replaced 4 times and the problem always returns
(usually in 6 months). I would say that the horn is getting wet and failing.

I guess I should add that the issues will not occur as long as I do not arm it. I could not tell from your post if it is going off when it is not armed. I just live with it now, by not setting the alarm. I just lock the car door with the small metal key in the key fob.

Last edited by dnlow; Jun 7, 2009 at 12:09 PM.
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Old Jun 7, 2009 | 02:47 PM
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Originally Posted by dnlow
This may not be your issue but I have had your problem ever since I owned my car for 4 years and it is was always the alarm horn in my case. I have had the horn replaced 4 times and the problem always returns
(usually in 6 months). I would say that the horn is getting wet and failing.

I guess I should add that the issues will not occur as long as I do not arm it. I could not tell from your post if it is going off when it is not armed. I just live with it now, by not setting the alarm. I just lock the car door with the small metal key in the key fob.
That would be a major PITA. The dealer should have to fix that as they obviously did several times under warranty.
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