MB alarm,help please

[bennesspipers]

Is there a simple way of disconnecting the alarm on my '95 202 C220 without upsetting the ECU etc ? its being a pain & going off for no apparent reason.

 

[grober]

On some dealer installed set ups you can silence the alarm unit under the bonnet with a key- doesn't prevent the alarm going off just the sound! At this time of year alarms are often triggered by spiders/insects inside the passenger compartment. You could try irradicating them or covering the motion detectors temporarily with tape.

edit:- mercfan beat my edit to it!

 

[MercFanUk]

202's are often set off by stupid things like spiders that live in the air vents etc - one of mine had that problem. I found the best way to stop it was to turn the interior sensors off. (Presuming you have the option, it would be with the rest of the buttons at the top of the centre console).

 

[andy27168]

I would be very reluctant to do anything electrically to disable the siren as this year of c class had an immobilser linked through the alarm and can be tempermental, and if it is working i would leave it alone if you can.
Try closing all air vents on leaving the car, and turnining off of the movement sensors, if you have no dashboard switch put some insulation tape over them.

 

[bennesspipers]

Thanx Grober,Mercfanuk & Andy27168. Dont think there is a dashboard switch,there is is key switch on the siren that stops it working when the battery is disconnected, i'll have to look into that, & apply some tape.

 

[bennesspipers]

There is a dash switch, but the owners handbook isnt very clear about its full function, or even if you touch the top or bottom of it to turn it off !!!! Anyone know the answers ? I have now taped the motion sensors up.

 

[MercFanUk]

The switch has two functions, one turns off the tilt detectors (for towing), and one the interior sensors (The imagery on the switch should show which is which).

All you have to do is press either up or down (depending on which you want to disable), before locking the car. A little light should flash in the switch to indicate that it's active.

 

[bennesspipers]

The switch just has a pic of a door inset with a key on the top half, bottom half of switch is just blank. I havent seen a flashing light on it.

 

[Howard]

That's the button to lock the doors ( or unlock them ) ...

Nothing to do with the alarm i don't think.

 

[andy27168]

That switch is to lock all the doors when inside if required, and has no red led's unlike other 202's
You more than likely have the same or similar alarm/immobiliser system as mine being a Scorpion fitted by either the importers or dealer when new.
There is a separate handbook for the alarm which tells you the procedure to turn off the interior motion sensors, too turn off motion sensors, remove ignition key, open drivers door, press the central locking dash switch in the unlock position and hold it till the red light in the rear view mirror lights up, then exit the car and arm system as normal.
To turn off the tow away sensor as well, after you have pressed the switch till the red light comes on press the switch again till the green light in the mirror lights up.
To turn off the towing sensor whilst leaving the interior motion sensors on, follow the procedures above and then press the switch for a third time till the red light lights up again.
This procedure "only" applies to prefacelift 202's with the red & green lights in the rear view mirror, though saying that some still had a dedicated switch for turning of the two alarm sensors, this procedure also may apply to 124's, 210's, 129's, the same alarm system was also fitted to the SLK 170 but you could,nt manually switch off the motion sensors as they would switch off automatically upon opening the roof, as a consequence of this and possibly others which i,m not familiar with it did,nt have the red & green lights in the rear view mirror.
Hope this has helped.

 

[bennesspipers]

Iv just followed your sequence,but the red light didnt come on (& i held it for a minute) , perhaps thats already off ??? Are all MB's as mysterious as this Aaaaaaagh !

 

[andy27168]

No it was because they decided to fit CAT 1 alarms to UK cars in answer to the demands of insurance companies and their hyped up premiums of the 90's, till they developed their own they turned to Scorpion for a bespoke alarm system for various models, these were available as standard or optional accessory.
You have to turn them off everytime you use the car and then get out as they automatically turn back on.
You tried the switch in the right direction?

 

[bennesspipers]

I pressed the bottom half of the switch, is that correct ?

 

[MercFanUk]

Heres an example of the OEM switches, so you can confirm if that indeed is what you have/don't have. You'd press this switch down to turn off the interior sensors.

 

[bennesspipers]

NO, my switch not like either of them, but i have found a MB leaflet which does indeed say that this is a Scorpion

 

[Dec]

Are your keys similar to mine?
The round key will turn off alarm? Siren? When turned a quarter turn in the alarm key lock which can be located ..
On siren, hidden under a weather cover…
Above your knees under steering wheel…
In glove box…
Or maybe else where in the cabin, most alarms have a means to turn them off if there is a problem.

Also inspect the alarm pin switch under bonnet as it can become rickety… bonnet can flex ever so slightly as it becomes hot then cools.

Dec

 

[bennesspipers]

Yes, my keys are like that. The round key does fit in the back of the siren, but all that does is isolate it when main car battery is disconnected. I cant find any other key holes.

 

[Dec]

When you turn the key in the siren you turn off either or both? The alarm brain and or the siren, that’s how it is with mine and no indicators flash (when locking) when the alarm/siren is switched off with that round key.

Regarding the Scorpion alarm key fob, on it, there is a slid switch on the side of the fob (not seen in picture)

When the slide switch is pushed in one direction, on locking the car, the internal motion detectors are disabled (off) and the indicators flash 2 times and alarm is armed.

When the slide switch is pushed in the other direction, on locking the car, the internal motion detectors are enabled (on) and the indicators flash 3 times and alarm is armed.

Dec

 

[bennesspipers]

Thanx for that info Dec, car allowed me to sleep last night so i must have done something right.