Hey fellas!

Got a little (or huge) problem. Today my car alarm turned on out of nowhere and it won't turn off. I had to pull the fuze (red 10), which also deactivated the lights within and locking/opening the car with the key fob. I don't know what caused this, but I might nead a hearing aid now, since this chirping sound definitely was not very comfortable to my ears
Can somebody point me in the right direction please?

Thank for your response!

Nick

 

There's a few threads on this.. various scenarios.. hate to say it but use the search feature of the board .. look for the threads with the most responses - they will be the most informative.

 

Read through most or all of them and did not find a suiting fit. On most of the threads the alarm turns on and off randomly and some can't start their cars. My car starts perfectly fine but the alarm always sounds...I pulled the fuze and as soon as I reattach it the alarm goes right off whether the ignition is started or not. Thought someone actually found a real fix for this problem!

 

Wasn't there one that was actually a bad alarm?

 

First place I would look is in the trunk under the foam, the central locking system/security module is there. Water leaks into this area can be tricky with the side effects.
Lift the carpet and peer down the forward end and look for a small swimming hole.

 

Hey guys!

I was gone for the weekend, just came back from Palm Beach just to find out I still have the same problem (doesn't come as a surprise that it didn't fix itself lol). Anyways, I looked in the trunk, but how do you remove the styrofoam without breaking it? What's the best way to go about it?

 

Look between the rear of the foam and side wall of the well, there is a slight gap with the foam slid toward the rear.

 

Sorry for being stupid but I still can't figure out how to take the foam out. lol jeeeeeez

 

That foam is a be-atch to take out. You have to remove the two upper rear inside trim pieces, the two lower inside trim peices, and then the lower center rear trim to get those foam inserts out. I literally cut the thing (right one) in four pieces VERY CAREFULLY to get to the central locking pump module. Anyway, the two right and left upper rear trim plus the lower center rear trim at the lock, then the two (left and right) real inner panels (lower) will give you the access to remove those two foam inserts.

I was able to slide the foam insert over a little before taking the drastic measures to cut the right one up though. I didn't see any water then but wasn't satisfied there was or wasn't any in there.

You can also pop a little hole into the rubber plug on each side accessable from the bottom of the car. They are positioned near the rear differential on the bottom of both compartments. Just get under the rear, you'll see both the plugs protruding. I would just stick something in there and pop a hole into it, then plug that hole with something you have. The plugs are thin so pushing something into it should be easy. You also might be able to use a single edge razor and slice a line into/through these plugs, if there is water there it should run out. Sealing the slice may or may not be neccessary, use your own judgement. I didn't pop the hole into it, as you see above I decided to tear into it from the top and hacked the foam into 4 (or was it 5) peices.

 

Got it! I'm going to take a look at this later on when I get back from work. Thanks for the explanation, I had the feeling I might have to take those 2 panels off in order to get the foam out. Damn car alarm! lol

 

I said you can look down the gap, any water should be visible. Stick a thin object down there, if it comes out wet you know you have a problem. Also, as GG said you can get under the car and pull a plug out. Taking the foam out should not be required unless you have water in the well.

 

Just a quick update of the situation:

I ended up taking the car to a mechanic I made good experience with in the past (not a dealership). He said he ran 3 different scanners to see what triggered the siren and could not get into the security system of the car. One of the scanners is the OEM Mercedes scanner which really surprised me. The bad news is that he said he doesn't want to take shots in the dark and the best thing to do was taking it to the dealership. The good news is that he cleared a few error codes that showed up and for some mysterical reason he said the alarm was not set off at all in the repair shop. Took it home and for 2 days I have not had any problems with the alarm system and everything works as is supposed *knock on wood*. I assume the problem is not really fixed but for now everything works out.
That makes me happy since the siren went right off every time I put the fuze of the alarm system into the fuze box. So far so good..

 

Well I'm having a similar problem. Mine has been going off randomly but will turn off if I lock then unlock with remote. I haven't checked the batteries yet, that will be tomorrow. But I also have the "cricket on crack" siren. My question is, could the malfunctioning siren itself cause the entire alarm system (lights flashing and everything) to go off? Is the siren a passive device that sounds when triggered by some other sensor and module or is it active where it can set off the alarm on its own. No water in the trunk, BTW.

Thanks.

 

Well, Dave and the other guys are probably right in thinking you have water getting into the trunk area. Once it dries out, your problems goes away for now, but it will start to corrode the components, then the real problems start. I would still investigate for water.

 

The siren can go titty up and need replacement due it sounding for no reason, if the lights flash as well I cannot remember, try a little search on that.

 

Having the same issue, haven't found a solution yet aside from not locking my car...

 

Yea, so the batteries in the remotes are @ 5.9-5.98 V out of 6 for the pair of pancake batteries in each remote. The car battery checked out good as well. I took the trim out of the passenger side of the trunk and really inspected the locking control mechanism. There is NO evidence that there has ever been water in the trunk. All the locks reliably work and everything clicks as it should.

I did a diagnostic on the alarm sensors as follows: I locked the car with windows down and open the drivers door...alarm sounded. Unlocked/ locked and opened the hood...alarm sounded. Unlocked/ locked opened passenger door...alarm sounded. Unlocked/ locked and opened glove box...NO alarm. I read somewhere in another thread that the glove box was alarmed also, but not sure.

Locking/ unlocking the car always (knock on wood) shuts it off and it has never come on while driving. Also, I have never had a problem with the car not starting from either a security or mechanical problem. NOTE: the previous owner had an aftermarket head unit installed. Is the radio wired into the security system.

I'm nervous about replacing the siren b/c if that's not the problem, instead of having just lights flashing and a crackling dying alarm, I'll have the thing blaring. Last night it went off at 2:30AM...I had my bedroom windows open so I head it and saw the lights flashing. I was hoping I could pull the alarm fuse and disable it (and the interior lights) but the door locks are part of that as well and I can't lock it. I'll just leave it at home unlocked and drive my other car until I figure it out.

 

!. Check the voltage of your starter battery (the big on under the hood). A weak battery can cause all kinds of wierd electrical gremlins.
2. Check and see if your liftgate closes properly on the latch. If you go over a bump slowly, such as a speed bump, and hear it knocking around, you hatch is loose and is causing the alarm to sound whenever. Mine did this and I fixed it by wrapping a few layers of tape around the latch post. No problem since.

 

Sounds like we have the same issue and no solution.. all I can say is you can pull the fuse and lock the doors manually.. honestly, I leave the car unlocked at home because I got tired of being woken up.. when I'm at work or out, I always lock it but have no idea how often it goes off.. pretty annoying

 

Hello! i just bought this car today and it has done this exact thing twice on me today , i just didnt lock it so hopefully it wont go off again , this makes no sense to me why it would be happening? mechanic checked it out today and said car was fine before i bought it , any ideas?