problem with alarm

[germanad]

I have a problem with the alarm on my w203
when I close it from the alarm of the key (closed lock) the car starts to sound and lights are activated as if he were stealing ha ha!
malfunctioning alarm. when I open it from the alarm of the key (open lock) or if I start the alarm goes off. any of you happened this problem?

 

[AndyPCD]

I would say there is a chance the siren is starting to fail. Very common problem.

 

[KillerHERTZ]

Yep, the battery inside the alarm sounds like its on its way out. If so you will need to swap it. Its located in the back of the front passenger wheel arch

 

[horgantrevor]

In the last few weeks their had Been 50 or so cars on this site and others with same fault siren

Easy fix

 

[A-AvantGarde]

In the last few weeks their had Been 50 or so cars on this site and others with same fault siren

Easy fix

+1 I changed mine last weekend

 

[germanad]

but also of the siren, flashing lights also light. siren be the problem?

 

[germanad]

I have this problem, but also of the siren, I have also the problem of flasher lights.
Anti theft siren goes off when I lock the car and leave! - Benzworld.org - Mercedes-Benz Discussion Forum
2000 s500 alarm problem please help - Benzworld.org - Mercedes-Benz Discussion Forum

watch this!
2000 s500 alarm problem please help - Benzworld.org - Mercedes-Benz Discussion Forum
I do not want to have that problem if I replace the siren.

 

[Vilus]

but also of the siren, flashing lights also light. siren be the problem?

The circuit board in the siren unit controls the alarm. It has two Varta batteries soldered onto it, which can leak. I was discussing it with my indie last week when mine was replaced. He said it almost as if Mercedes engineer certain parts to fail and require replacement. Alarm siren failure is so common he keeps them in stock!

 

[Dec]

Unplug the siren, if the faults that you have of the siren sounding and hazard lights flashing stop, then it will prove that the siren is at fault.

Here is an example of what happens to these alarms after about 10 years, see… http://mbworld.org/forums/sl-class-...goes-off-no-reason-kills-battery-fix-diy.html

Mine was like the above when I replaced it last year, you are never more than a mile from a faulty alarm.

Dec

 

[A-AvantGarde]

I have this problem, but also of the siren, I have also the problem of flasher lights.
Anti theft siren goes off when I lock the car and leave! - Benzworld.org - Mercedes-Benz Discussion Forum
2000 s500 alarm problem please help - Benzworld.org - Mercedes-Benz Discussion Forum

watch this!
2000 s500 alarm problem please help - Benzworld.org - Mercedes-Benz Discussion Forum
I do not want to have that problem if I replace the siren.

As others have advised, it's almost certainly the siren itself at fault - it's a very common problem.

If you unplug the siren it should allow you to lock the vehicle without the lights flashing continuously or the alarm sounding. Naturally your alarm won't function but it will allow you to lock & unlock the car properly.

 

[germanad]

I'm going to list the faults with the car alarm has:
1: I close with the fob, when I open it with the fob position lights and the headlights are lit auxiliary only go off if I open the driver's door.
2: I am in the car, I close with the fob, I move in the car, turn on the radio and the alarm does not sound, no lights flash.
3: open the window, I close from the fob, stick my head inside, no alarm, no lights
4: I close from the fob, open the driver's door with the key of relief (metal) and alarm lights begin to flash. but no siren.

 

[germanad]

I forgot. when I close the light is flashing red button trailer.

 

[Dec]

I'm going to list the faults with the car alarm has:
1: I close with the fob, when I open it with the fob position lights and the headlights are lit auxiliary only go off if I open the driver's door.
Alarm siren failure.

2: I am in the car, I close with the fob, I move in the car, turn on the radio and the alarm does not sound, no lights flash.
Alarm siren failure.

3: open the window, I close from the fob, stick my head inside, no alarm, no lights
Alarm siren failure.

4: I close from the fob, open the driver's door with the key of relief (metal) and alarm lights begin to flash. but no siren.

The metal key blade is for emergency entry into the cabin via the driver’s door or to open the boot, unlocking a car that has been locked electronically with the remote fob will cause the alarm to sound and hazard lights to flash when the door or boot is opened.

The metal key blade is completely mechanical and is intended to open the car in an emergency , for example, if the car battery is flat or the remote fob or central locking has failed.

See also, pages 79-80-81 here… http://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/ownersmanual/2003_cclass.pdf

Page 81 above may explain the “flashing Red Button”


Dec

 

[germanad]

fine, remove the bell, I have in my hand.
even without the siren, continue on and off the flashing lights. Position continue latching on the lights. did not change anything. no way to measure the siren with the multimeter?

 

[Dec]

Is your alarm siren like either of the two Black sirens pictured below?

Dec

 

[Dec]

fine, remove the bell, I have in my hand.
even without the siren, continue on and off the flashing lights. Position continue latching on the lights. did not change anything. no way to measure the siren with the multimeter?

Which lights do you mean?

Dec
Source… MERCEDES C CLASS W203 HAZARD SWITCH LOCK CONTROL SWITCH | eBay

 

[germanad]

flashing ligths = hazard lights

yes, the siren is similar of the photos. in my country it sales for 460 dls!!

 

[Dec]

Do the hazards flash ONLY when you unlock or lock the car?
Lock = 3 Flash of hazards, all doors lock.
Unlock = 1 Flash of hazards, all doors unlock.
Do the hazards flash at any other time other than when locking /unlocking?

Does the inside cabin light come on when you open ANY of the doors?
Are there any other electrical faults?

I can’t remember if the hazards should or should not flash if the siren I disconnected? (unplugged)

Dec

 

[germanad]

Lock = 3 Flash of hazards, all doors lock.
Unlock = 1 Flash of hazards, all doors unlock.

YES, ITS OK!

Does the inside cabin light come on when you open ANY of the doors?
Are there any other electrical faults?

YES, THE ROOF REAR LIGHT COME ON WHEN I OPEN REAR DOORS. AND THE FRONTROOF LIGHT WHEN I OPEN FRONT DOORS
ELECTRICAL FAULTS, WHEN I UNLOCK DE CAR, HEADLIGHTS COME ON, AND ONLY COME OFF IF I OPEN DRIVER DOOR.
ALARM NO SOUND
IF I AM INTO THE CAR AND I LOCK THE ALARM, IT NO STAR (NO SOUND, NO HAZARD)

 

[Dec]

flashing ligths = hazard lights

yes, the siren is similar of the photos. in my country it sales for 460 dls!!

When you unlock the car do the headlights stay on for a long time or just a few minutes?
I still think you have a faulty siren, don’t know if the headlights staying on is a fault or not.

Siren in UK should be about £80 or €100...$460… what country is this?

Dec