W124 key explanation please

[Makdissy]

Hi guys
I know there are 3 different types of keys
1: main with square plastic part
2: valet key, oval shape
3: flat, just metal small key to fit in your wallet.
Now the question is: I have a tiny small key, which looks like a safe key or key for a bicycle lock, I can provide a pic if you don't know what I am talking about, but I'm sure many w124 owners understand me here, anyway I have a little lock in my glove compartment ( I can lock or unlock ) with this little key, but it doesn't make any difference what so ever, I feel like throwing the stupid thing away, but before doing so and regretting it all, I thought someone might be able to explain
Many thanks

Oh, by the way I have a little autowatch fob ( just a plastic bullet with no buttons )with the keys and I can't start the car without.

 

[GP801]

Sounds like you have an aftermarket alarm/immobiliser. The fob thing is probably the transponder. The key may be the key to disable it.

 

[Makdissy]

I tried that, thinking its to disable the immobiliser, but no luck, without the fob I can't start the car, so the key is useless in on or off position

 

[Makdissy]

Thinking about it, the previous owner mentioned the car has a scorpion alarm system, but never gave me any fobs or remotes, could it be related???

 

[Dec]

A Scorpion alarm may have a round key to turn off the alarm via a keyswitch, as you describe, is your key round or flat?
The plastic bullet, as you say, must be an immobiliser.

It would be useful to reveal what year the car is?

Dec

 

[Alex Richardson]

Thanks for the photos. Makdissy should upload few photos. And why the previous owner refuse to give you the fob or remote for the scorpion alarm system? I think you deserve to have it mate.

 

[Makdissy]

hi again everyone and thanks for your reply, really sorry to confuse you all but im lost my self with what other owners done to my beautiful Mercedes, here is a pic with all bits and bobs I have in my car including stickers ETC...
its a 25 years old puzzle, and I hope with your help we can solve it, im sure the car left Mercedes dealers with fitted alarm, there is a sticker to prove that (pic no: 8 ) and the previous owner told me there is scorpion alarm fitted , so please take a look at all the pictures and let me know whats what and what needs removing and what seems to be working at the moment!!!
many thanks

 

[Makdissy]

Alex, I think they were lost or damaged.

 

[Makdissy]

A Scorpion alarm may have a round key to turn off the alarm via a keyswitch, as you describe, is your key round or flat?
The plastic bullet, as you say, must be an immobiliser.

It would be useful to reveal what year the car is?

Dec

she is A124 cabrio 1993

 

[GP801]

The autowatch transponder is like one we had in a previous car. The immobiliser is disabled by turning the ignition on and off after a set number of blinks of the little red light in a special sequence. Without the code I dont think you will succeed. The other one looks like a siren disable for the alarm. The two systems are probably not linked. Security on these cars is pretty dreadful so personally I would keep the immobiliser.

 

[Dec]

There are the possibilities that the alarm is disarmed or armed when the central locking is operated with the key in the door, this negates the need for a remote fob to arm/disarm the alarm.
If the alarm is not in working order and turning it OFF or ON with the round key in the glove box has no effect, this idea is supported by the fact that the bottom LED does not illuminate to show that the alarm is armed after the car is locked with the key in door.
However, it is just as likely that there was originally a remote fob like the one in my picture… which is a 1994 car… and it has become broken or lost or forgotten about as the car changed hands over the years.

Picture 3 is motion sensors, one of which may have a LED which will flash if it detects motion inside the cabin, I think this LED is also used for adjusting the sensitivity of the motion sensors.

The top LED must be for the auto watch immobiliser, perhaps the auto watch was fitted to compensate for the non working alarm.

Does the central locking lock/unlock all doors when the car is locked by key in the drivers/passenger doors?
Is there an alarm siren in the engine bay, and if so, how many wires go into it?

Dec

 

[Makdissy]

hi again, I hope this pic helps

 

[Makdissy]

by the way, I had a problem not long ago with my battery ( used to go flat if I don't start the car every 2 days ) took it to merx in stoke and I was told the alarm system was the problem, now the alarm is no longer connected but I had no fob or remote for it anyway.
Dec, to answer your question: no , the key doesn't lock all doors and boot, it seems like my central looking pump connected to the alarm that's not in use .

 

[E55BOF]

If it's like my 1994 R129, and I suspect it is, if the OE alarm/immobiliser is armed with the infra-red flip key fob, the central locking is disabled until the alarm/immobiliser is disarmed the same way.

 

[roadhog]

View attachment 57600

Pics 1,2,3 and 8 are the dealer fitted alarm, probably Scorpion.

View attachment 57619

As is the siren, the lower of the two LED and the two motion detectors mounted on the A pillars.

The Scorpion alarm needs the little key fob in the centre of that pic to arm/disarm. It won't work off the door locks.

The little round key, as you have already found out, goes with the lock in the glove box. On my cars it disables the motion sensors. I guess it could be wired to disable the siren but I don't see why you'd want that. Since you don't appear to have the remote, the little key has no effect on anything as the alarm can't be armed.
I've no idea whether you can still get a replacement remote. My guess would be that it might make more financial sense to ditch what you have fitted and fit a more up to date system. I'd remove the Auto watch gizmo with the bullet shaped key fob at the same time.

... it seems like my central looking pump connected to the alarm that's not in use .

It's usually the other way round, the alarm sends a signal to the existing vacuum pump. There'll be another reason why you can't lock all of the doors with the key. It could be something simple like a disconnected hose. Maybe something was disturbed when the alarm was disconnected.


RH

 

[Dec]

Your pictures are very useful, thanks… that look like 334 on the siren, I’d say that alarm of yours is the same as I had on my old 1994 W202… first picture.

In the centre of the second picture below you can see the alarm control box, you must have one like this somewhere too, perhaps under the cluster in the same location as the one pictured below or elsewhere in the cabin.

I think that alarm is indeed missing a 2 button remote control fob.
One thing you should know about that alarm, if the car battery is disconnected and when the car battery is reconnected, then the alarm will re-arm itself, this is normal, an anti-tamper feature, however, if the alarm is switched off, with the round key, then re-arming wont happen if the car battery is ever dis-connected/re-connected.

The alarm siren is probably rusted inside and is/was causing the battery drain, it would be wise to unplug the siren just in case.

The alarm system would be connected to the vacuum pump under the rear seat, have a look for any additional wiring from the alarm that would have been spliced into the vacuum pump wiring.

How long have you owned the car?


Dec