midlife

Hi
I am based in Aberdeen Scotland and during the last few days is has been raining heavily. Today whilst sitting in my office my alarm kept going off. I tried to convince myself that the alarm might just be to sensitive with heavy trucks going past, setting it off however when I think about it, a month ago the same thing was happening and it was raining then also.

I checked the carpets to see if they were wet and I'm glad to say they are fine but the only thing I can think of is that the water is getting in to a fuse box or something

Anyone got any thoughts about what could be triggering the alarm.

ALLDATAdiy INFO

Possible defective motion sensor on the interior?

Possible defective ultra sonic sensor on the roof?

I imagine a hard rain could magnify either of these.

blas0827

it can be your siren for the alarm

SUNILP

motion sensor and ultrasonic sensor are the same sensor. I would do a diagnostic scan to see what is triggering the system. Could be siren as mentioned and or PSE

midlife

Thanks for the replys guys. Last night the rain kept coming down and the alarm kept going off so I left it unlocked. I then went outside and disarmed (don't know the name of the switch) the switch that you press for being towed and since I did that the car has locked without the alarm going off. Does this help with any of your suggestions i.e. does it pin point the fault?

whoover

No.

It can still be the alarm siren, the sensor, the PSE or something else. Your car has stored codes which, when read by dealer, will probably diagnose the fault. If not, they can pinpoint it easily. You really should just let them fix it rather than mask the problem. Your other alternative is to disable the alarm everytime you lock the car.

midlife

Cheers whoover. I'll be getting the car in to the dealership next week to get it checked on STAR as I think I still have an issue with the airmatic pump (even though the leaks from the struts are repaired!)
I'll follow up on the forum after I find out whats up

jon_oldman

I just managed to solve this problem on my 2003 S500, so thought I would post on this old thread.

My alarm kept going off in the middle of the night -- lights flashing and alarm (not horn) blaring. The buttons on the key fob didn't stop the alarm. Even unplugging the battery had no effect on the siren.

As it turns out, my trunk hinge and latch are slightly out of alignment, and when it gets cold and wet outside, somehow the latch triggers the alarm. I went outside and pushed down hard on the trunk, and was able to turn of the alarm. I've also seen posts out there that talk about the door latches doing this exact same thing.

Neighbors and I are simpatico again!

malahhaor

If it does not go off when tow away alarm is disabled it could be the tilt sensor. I had a problem in my Clk where it would go off randomly. Friend at dealer told me after scanning thet the sensor/ball was bad that monitors tilt and shock. I sold the car before I got to fix it though.

tusabes

its probably not related, but make sure your drain under the hood is clear since its been raining

Wendyalvarez

mine does the same thing. Not sure why. I’ve changed the batteries on my fob numerous times thinking it may be that but hasn’t changed anything. I hope we can find a solution soon! It’s becoming annoying. I literally have to have my key fob on me all the time so I can turn the alarm off.