Hi all, I hope someone can help.
I have a 2004 (face-lift model) C Class Estate. The alarm keeps going off after I have been driving in rain or when raining heavily. The only way to stop it is to wait for a break in the alarm sound and lock the car manually with the key and hit the two alarm override buttons on the dash. (interior motion detectors & anti tow away). The alarm doesn't stop when the car is un-locked, it goes on relentlessly.
A friend who worked at a Merc dealership has fitted a new alarm sounder and wiring loom (as per Mercedes diagnosic) , however this hasn't solved the problem. The two keys also had new batteries, so that can be eliminated.
Has anyone else had this problem?? Its making me very un-popular with the neighbours.
Thanks for reading.

 

I have a C240 2003, which I had the same issue as you described. The difference was my car alarm was acting like that when the weather got really cold. (I live in North California, and we have cold winter nights here). I found out that the connector condenses/gets moist and that coused the issue... I think you have similar issue, it could be the connector for siren it self that needs to be opened, and cleaned and dried off properly. If you can seal the connectors when closing it.


Thanks
kenz

 

Thanks for that KenZ


A hair dryer &good glob of electrical grease could be the answer then.

I'll give it a go.

Regards