C200 Alarm Problems

[rcmercedes]

Can anyone help?

My C200K (2001) has started waking me up in the middle of the night by sounding the auxilliary alarm siren for no good reason. I turn the alarm off, go back to sleep and off it goes again 20 minutes later, but it's clever, and resets itself so that it can wake me up again!!! I finally win by getting dressed and opening one of the doors.

When investigating, I pushed at the wires going into the siren (mounted under the N/S wheel arch) and off it went. I pushed the wires again and it died completely. So I replaced the siren. Now I can't get anything out of the new siren. I've traced the wires from the siren back to the rear SAM, but at £170 + VAT a time, I'm not sure if I'm heading in the right direction. The alarm sets okay, central locking works, everything else is fine. Any ideas welcome. Also does anyone know where I can get a wiring diagram?

rcmercedes

 

[panason1c]

Dont know if this helps but our C200 (1999) suddenly started sounding the MB factory alarm randomly during the night (i had never previously had a false alarm), sometimes it would only go off the once....or it might sound a couple of times, this pattern continued for a few nights. I asked MB what could be causing the false alarms but they didnt have any clues and suggested that they 'look at it', ...As i didnt feel much like spending £80 an hour i investigated the problem and discovered a moth inside the car was the culprit!....it was flying about during the night and triggering the ultrasonic (glass breakage) detectors!!......i wasn't convinced at the time that the moth was the cause of the false alarms but since removing it i had no further problems for the following six months when i then sold the car.

 

[piestore]

203 siren fault

Hi it is very common for the siren plug to suffer from water ingress. I have also had a few cars where the loom has been faulty of chaffed

good luck

 

[baj25]

I've had the same problem on 2000 C180- not popular in the middle of the night on a French campsite, believe me! MB could tell me when it went off and which sensor triggerred it, but had no idea how to stop it. I usually turn off the sensors now after it happens once (button on dash + ignition key sequence, explained in owners manual).

 

[joe bloggs]

I think you have fixed it with the new siren, was the wiring ok? The new siren will need set up by the dealers star machine before it will do anything