The security alarm on my 04 clk 500 activates randomly and using the smartkey, pressing the lock/ unlock button doesn't stop the alarm. THe alarm is loud, obnoxious and embarrassing. I've called the nearest MB dealership and they told me that the a module related to the alarm has gone bad or shorted out, however they also told me that my car wouldn't start with the shorted out module. My car starts while the alarm is activated, so I'm confused as to what is causing this issue. Please help me so that I don't have to spend tons of money on my psychotic car!!!!

 

Interesting.
The alarm works BUT will not turn off despite still being able to start the car.
Long shot: Do you have the internal pressure sensing alarm enabled? If so this can be disabled and MAY make a difference.
I guess the dealer is most probably correct that the PSE module has gone down. (quite a common failure)

Best way forward is to get the car STAR DIAGNOSTIC checked.
Get the dealer to do a "Quick Check" which will cost a small amount (15mins) and get a PRINTED report.
This report SHOULD identify codes pertaining to the errant alarm and confirm that the PSE module is at fault.
PSE modules are in the ball park 300USD + fitting. Fitting is a very simple job.

Stuart

 

IF VEHICLE STARTS & SIREN DOES NOT GO OFF WHEN ENGINE IS STARTED YOUR ISSUE IS W/ THE ALARM SIREN ITSELF. IT IS POWERED & TRIGGERED BY THE VEHICLE BUT ALSO HAS AN INTERNAL BATTERY THAT WILL LET IT GO OFF BY ITSELF W/ VEHICLE BATTERY DISCONNECTED. YOUR PROBLEM IS NOT W/ THE PSE MODULE!!YOU MOST LIKELY HAVE WATERIN ALARM SIREN.