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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53979
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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2004 SLK230 Kompressor. Alarm making continual pulsing high

Customer Question

2004 SLK230 Kompressor. Alarm making continual pulsing high pitched short bursts that starts and stops at random. Started when car was off and locked. and a few minutes after I left the car. The "pip-pip-pip" sounds continued for 40 minutes before I came back to the car from the restaurant. When the car was started and driven home the bursts continued for 5 or so minutes and then stopped. The battery is disconnected now that I am home.
JA: How many miles are on the car? Has this ever happened before?
Customer: Car has about 94000 miles. Never happened before.
JA: Are you fixing your SLK230 Kompressor yourself? What have you tried so far?
Customer: Have not tried anything regarding this yet. I have resoldered the K40 relay soon after I bought the car in 2010 when I had the starting problem. No more startying issues since then.
JA: Anything else you want the mechanic to know before I connect you?
Customer: The noise has not recurred since disconnecting the battery yesterday.
Submitted: 11 months ago.
Category: Mercedes
Expert:  Marty replied 11 months ago.

Hi, welcome to Just Answer. My name is***** problem is usually caused by a faulty alarm siren. There is an internal battery in the siren that will fail and cause the siren to act erratically. Replacing the siren will more than likely solve this issue. Another possibility is a faulty PSE module located in the trunk. Water can find it's way into the PSE module and cause erratic behavior or the siren. It is more likely that the siren is faulty.

Let me know if you have any questions.


Customer: replied 11 months ago.
Where is the siren located in the car? This car has been in California since 2010 and chance of water getting into the PSE module is very low. Is the battery in the siren independently replaceable?
Expert:  Marty replied 11 months ago.

The siren is located under the wiper cowling at the base of the windshield next to the wiper motor. The battery in the siren is not serviceable.