W202 Scorpion security alarm

[dragon]

Could someone please enlighten me with this faulty security module.

It currently gives a fault alarm and therefore I have not arm it and just used the mechanical key to lock it except on short trips say to supermarket because I don't want my fuel being siphoned off.

What happen if I discount the two electrical plugs to it? Will I be able to start the car? How do I disable this module if it develops a fault if I can't start the car?

If I managed to source a similar module from crashed car sites, do I also need the key flobs that came with it?

I remember fitting it to my wife W201 from an aftermarket Scorpion security alarm system from Lucas, there is a key you can disable/enable the security system. This one fitted to W202 doesn't seemed to have this feature.

 

[bigbobs CL]

If the immobiliser circuit is connected then you won`t be able to start it with the plugs out. There is a way to by-pass that but i`m not going to post it on a public forum!!!

If you found another alarm then you would need the remotes, however if you open the alarm up there will be a small sticker on the PCB with i think a 6-7 digit code. This is the code for the remotes and replacements can be ordered using this code.

Have you any idea why it`s false alarming? Might be worth adjusting the ultrasonic sensors using the small silver screw on the back of the alarm unit.

Bob

 

[dragon]

If the immobiliser circuit is connected then you won`t be able to start it with the plugs out. There is a way to by-pass that but i`m not going to post it on a public forum!!!

If you found another alarm then you would need the remotes, however if you open the alarm up there will be a small sticker on the PCB with i think a 6-7 digit code. This is the code for the remotes and replacements can be ordered using this code.

Have you any idea why it`s false alarming? Might be worth adjusting the ultrasonic sensors using the small silver screw on the back of the alarm unit.

Bob

I thought it a well known fact the false alarming is due to the Scorpion security module spikes when connecting back the negative of the battery. I tried masking the sensors with black wrapping tape and it still happening.

What the likely I won't be able to start the car because the module is faulty and then what I should I do?

I brought the car back to use for half a month now the fault alarming haven't happened yet because I know if it did, the red light will flash instead of the green on un-arming the car. I haven't leave it long enough arming it because I didn't want to disturb my neighbours in the middle of the night or occupants around the area I parked if I am in London. I didn't want to take a chance and get my car towed off.

 

[bigbobs CL]

Spiking can cause faults in the alarm but ones i have come across just blow the whole thing!

If your alarm unit completly fails and you can`t start the car then as i said it can be by-passed if you know which wires to by-pass but i won`t post how to do it. Let me get a few more posts so i can send PM`s and i`ll tell you.

Bob

 

[dragon]

Spiking can cause faults in the alarm but ones i have come across just blow the whole thing!

If your alarm unit completly fails and you can`t start the car then as i said it can be by-passed if you know which wires to by-pass but i won`t post how to do it. Let me get a few more posts so i can send PM`s and i`ll tell you.

Bob

Thanks Bob.

 

[bigasotonuk]

Hi,
Not every Scorpion alarm can be bypassed this way, you may find that your immobiliser, is done through a transponder fitted in the key fob and when in proximity of the collar around the ignition key switch disables it via the ECU.
I believe the lower models came from the factory with a factory fit immobiliser as described above.
One of the dealer fit items at time of purchase was for an alarm system which would of been fitted for the customer if required, this alarm system would have been fitted as an accessory This system is completely separate from the immobiliser in this case and utillisies the infra-red locking signal from remote C/L fob.
The fob sends 2 codes to the car, one for the locking, and the other for the alarm only (in the case of cars fitted with the immobiliser described as above) or Thatcham alarm/immobiliser, one of the these codes is a rolling code and this is what is synchronised to the key when the synching procedure is followed.
In case of the Immobiliser as described above there is no known way of bypassing this. Items of the immobiliser system are, i.e. key chip, ignition switch ring, E.C.U. can be potentially expensive if it were to become faulty sourcing second hand items involve a purchasing the E.C.U. and key fobs from the same doner car.
I have found that this type of immobilser is fitted mainly pre face lift C180's and C200's,
if your ECU is fitted under the washer bottle i,d be willing to bet you have this sort of immobiliser.

 

[bigbobs CL]

If I managed to source a similar module from crashed car sites, do I also need the key flobs that came with it?

This tells me he has a seperate alarm system with its own remotes, in which case the immobiliser can be by-passed how i said.

An upgrade alarm which uses the cars existing remote locking will be different and may not have an immobiliser as you said but be built in to the ECU.

These work by picking a signal up from the cars central locking signal wires, not from the fob sending 2 different codes, usually 2-1 upgrades if your car has a Cat2 immobiliser as standard and you want to upgrade it to Cat1. This can only be done if your existing remote has rolling code built in, it can`t be fitted and properly classed as a Cat1 if they are fixed codes.

Bob

 

[bigasotonuk]

My C230K has a Thatcham approved alarm (Scorpion fitted by MB and has MB pt. no.'s) according to my Insurance company and has a separate alarm Control Module and can be bypassed via this module by shorting out 2 cables.
A genuine MB accessory alarm still has a control module which visually looks the same as mine (different pt. no. though), and it was these that were fitted if the car had the immobiliser with the chip in the fob.
So to simplify things 2 different type of alarm systems were available from MB both Thatcham approved one with immobiliser and one without. The alarm without the immobiliser was fitted to the vehicles with the chip in fob immobiliser. Cars without the chip in fob immobiliser, were fitted with the alarm with the immobiliser feature.
The fact that these fobs will not work straight from MB and have to be synched shows that these fobs do indeed produce a rolling code, this information regarding the rolling codes was given to me by a MB tech in 2003, he was actually old enough to of worked on them when they were new so was talking from experience.

 

[bigbobs CL]

The fact that these fobs will not work straight from MB and have to be synched shows that these fobs do indeed produce a rolling code, this information regarding the rolling codes was given to me by a MB tech in 2003, he was actually old enough to of worked on them when they were new so was talking from experience.

I was talking in general about rolling codes, Mercedes do have it as standard but most upgrade alarms work from picking up a signal from the central locking wires, ie, lock the car arms the alarm, unlock turns it off. These do have to be programmed into the car and won`t work straight out of the box.
I`ve been fitting alarms for 16 years and can`t see a scorpion one being fitted to a Merc would be any different to fitting one to another car.

the only reason i said it could be by-passed the way i described was because Dragon asked if he needed the new remotes if he replaced the alarm unit. If he has an upgrade alarm then by-passing the factory fit immobiliser as you said would need to be done at the dealers and not quite as easy!!

The older Mercs always had scorpion as standard and were always getting taken off as the alarm box was always on the n/s strut, always got full of water and buggered up!

Bob

 

[dragon]

I was talking in general about rolling codes, Mercedes do have it as standard but most upgrade alarms work from picking up a signal from the central locking wires, ie, lock the car arms the alarm, unlock turns it off. These do have to be programmed into the car and won`t work straight out of the box.
I`ve been fitting alarms for 16 years and can`t see a scorpion one being fitted to a Merc would be any different to fitting one to another car.

the only reason i said it could be by-passed the way i described was because Dragon asked if he needed the new remotes if he replaced the alarm unit. If he has an upgrade alarm then by-passing the factory fit immobiliser as you said would need to be done at the dealers and not quite as easy!!

The older Mercs always had scorpion as standard and were always getting taken off as the alarm box was always on the n/s strut, always got full of water and buggered up!

Bob

When are you going to pm me the solution?

I need to try it out to ensure it works not in the middle of busy London if it broken down.

 

[bigbobs CL]

When are you going to pm me the solution?

I need to try it out to ensure it works not in the middle of busy London if it broken down.

When the forum admin allow me to!!!

Bob

 

[dragon]

When the forum admin allow me to!!!

Bob

Oh you need at least 50/100 postings.

 

[dragon]

That a very good write up and I got a better understanding of how the system works. Thank you.

What bugging me is the Scorpion module was installed after I agreed to purchase the car from new. If the immobiliser depends on the Scorpion module to enable/disable self, how did they managed to get it to UK from Germany without the Scorpion module fitted?

 

[bigasotonuk]

Scorpion alarms of the 96-97 cars were specifically and exclusively designed and made for MB and were even given MB pt. no.'s and were designed to interface with the vehicle systems.
Scorpion alarms and alarm/immobiliser's were fitted for the UK market by either the selling dealer, or like in my case by the Importer, i.e. in the UK.

 

[dragon]

Hi,
Not every Scorpion alarm can be bypassed this way, you may find that your immobiliser, is done through a transponder fitted in the key fob and when in proximity of the collar around the ignition key switch disables it via the ECU.
I believe the lower models came from the factory with a factory fit immobiliser as described above.
One of the dealer fit items at time of purchase was for an alarm system which would of been fitted for the customer if required, this alarm system would have been fitted as an accessory This system is completely separate from the immobiliser in this case and utillisies the infra-red locking signal from remote C/L fob.
The fob sends 2 codes to the car, one for the locking, and the other for the alarm only (in the case of cars fitted with the immobiliser described as above) or Thatcham alarm/immobiliser, one of the these codes is a rolling code and this is what is synchronised to the key when the synching procedure is followed.
In case of the Immobiliser as described above there is no known way of bypassing this. Items of the immobiliser system are, i.e. key chip, ignition switch ring, E.C.U. can be potentially expensive if it were to become faulty sourcing second hand items involve a purchasing the E.C.U. and key fobs from the same doner car.
I have found that this type of immobilser is fitted mainly pre face lift C180's and C200's,
if your ECU is fitted under the washer bottle i,d be willing to bet you have this sort of immobiliser.

If you know the answer PM me please. You can ask Malcolm as my referee.

 

[dylanbatt1139]

If the immobiliser circuit is connected then you won`t be able to start it with the plugs out. There is a way to by-pass that but i`m not going to post it on a public forum!!!

If you found another alarm then you would need the remotes, however if you open the alarm up there will be a small sticker on the PCB with i think a 6-7 digit code. This is the code for the remotes and replacements can be ordered using this code.

Have you any idea why it`s false alarming? Might be worth adjusting the ultrasonic sensors using the small silver screw on the back of the alarm unit.

Bob

i have a problem with my 1996 w202 c200, the immobiliser will not turn off
i drove to work fine set the alarm etc all ok
i came out of work this morning and the alarm disarms but green light is flashing fast ,no red light and cant start car
i spent a few hours trying to fing imob to bypass it to get me home with no joy
it cost me £75 in a taxi from worksop to manchester
do you know of a way to bypass it so i can pick up car
i would be very gratefull for your help

if you do not want to post the answer for obvious resons my email is info@dsbcontrols.co.uk

hope you cxan help

 

[bigasotonuk]

Try replacing the fob batteries in the first instance, even if the fob still unlocks the car, disconnecting/reconnecting the battery has been found to work. When these cars were newer and MB actually knew how to fix these they told me that 95% of the problems were caused by flat fob batteries, defective fobs and the red and green lights in the rear view mirror being blown.
As far as bypassing the immobiliser there were different types fitted to this vintage C class, so the solution is,nt always the same for every car and as they were fitted after build the immobiliser circuit could be any one of 3-4 different circuits, depending on the fitter.
Call the AA out when mine failled they had all the information on how to bypass it in a laptop, 5 minutes after arriving the car was running.

 

[dylanbatt1139]

Thanks for that info i am going to try the above i have a spare key fob so i will take that with me

this thing i keep heering about the red lights on the door and the mirror
mine has a green one on the door should there be a red aswell, only if it has one is dose not work
also the red one on the mirror now does not work??

can theese realy affect the imobiliser?



any way thanks for answering my questions i will let you know how i get on


thanks dylan

 

[television]

I cant see the batteries in the remote as a problem, though the remote sends a RF and IR signal, the car has accepted the signal, I could be wrong. I will also look up the coding

 

[bigasotonuk]

Hi,
The red light not working in the rear view mirror does effect the operation of the Alarm/immobiliser, I know this for a fact as it had to be replaced in my C230K 1997, the door red & green lights I,m not sure of but when mine failled I replaced it straight away as I did,nt want to be caught out.
The Scorpion Alarm/alarm, Immobiliser fitted to this vintage Mercedes required no coding though the factory fitted Immobilisers (used and worked in conjunction with the Scorpion Alarm only installation) fitted to some models did.
Another common fault with these alarms was the siren and the back-up battery being U/S.
Regarding the fob batteries I still have problems with mine occasionally, when the immobiliser plays up, a new set of batteries in the fob and everything works as it should.
This happens everytime the fob batteries go flat in my car. The additional MB handbook which came with the car even says to keep a spare set in the glove box.