W212 Alarm sounds shortly after locking car

[TeddyRuxpin]

Hi,

My W212 has sat for a while while I'm using another. It's been kept locked. Much of the time the battery has been on a trickle charger. I take it off sometimes.

The other day the trickle charger was on it and I went and removed something from the boot. After I locked the car again, the alarm now sounds when I leave it for more than 3-4 mins.

I removed the battery charger, no change. I tried pressing the tow button and the interior sensor, no change. Any ideas what could be up?

I will try to start the car up for a few minutes - but the car is not currently taxed so I can't take it for a spin.

I currently have to travel away and don't want to have to leave the car without locking it. I was thinking of locking it then disconnecting the battery, which should resolve the issue until I return?

Thanks!

 

[TeddyRuxpin]

I started the car up and let it idle and get up to temperature, I live on private farmland so was able to move the car round a little bit, but nothing over about 10 or 15 miles an hour. I also used my MB 2.0 to scan for codes and there were no issues.

The problem persists.

Any ideas?

 

[BlackC55]

You need to have a look at the reason for the activation. There is a menu in one of the SAM units that will tell you.

 

[TeddyRuxpin]

Thank you for replying - I've tried to read as many codes as I can using my MB 2.0 but there were no errors. I will try to deep dive into any more sections but I couldn't find anything related to the alarm. I checked every 'section' on the computer, but perhaps I need to go into read some kind of live data?

I'm sure proper mechanics such as yourself have better tools to read, but I didn't really want to have to tax and insure the car in order to resolve the issue as I'm using another W212 at the moment and the whole point was to try to save money!

I'll go back in a moment and see if I can investigate further, thought I don't even know which section the alarm is under.

 

[BlackC55]

I think its in the rear SAM. You are looking for Alarm activations.