1995 C200 Immobiliser fault

[paininthecclass]

Hi my w202 c 200 has an acting up immobiliser does anyone know how to bypass it?
thanks

 

[paininthecclass]

someone please help!!!!!!!

 

[bigasotonuk]

Hi,
Welcome to the forum.
How do you know for definite that its the immobiliser playing up?
I take it that your key is a single button remote with a flip out key.
Have you tried fixing the alarm system rather than bypassing it?
Did you try your spare key?
It can be bypassed, Mercedes told me how to bypass mine, also when I called out the AA they knew from one of their tech books.

 

[paininthecclass]

Hi,
Welcome to the forum.
How do you know for definite that its the immobiliser playing up?
I take it that your key is a single button remote with a flip out key.
Have you tried fixing the alarm system rather than bypassing it?
Did you try your spare key?
It can be bypassed, Mercedes told me how to bypass mine, also when I called out the AA they knew from one of their tech books.

Hii cheers, i got a new key which is programmed to the car it unlocks the doors centrally via remote, i had a problem with the limp home mode it kept activating and a diagnostics showed the immob was intermitant and should be short circuted but the auto electrician wanted £100 to do it.
so its left me stuck with no car.

 

[bigasotonuk]

Hi,
The immobiliser on this year has nothing to do with the diagnostic side of the vehicle as all it is an aftermarket Scorpion Alarm fitted to the vehicle by MB once it was in the UK.
If it was the Immobiliser at fault the engine would completely die not just go into limp home mode.
If the Immobiliser was at fault the diagnostic would,nt read any codes in the ECU at all as the immobiliser cuts the power supply to it.
I think you have an ECU problem personnally, to be completely honest i don,t think your car will even be equipped with a limp home facility because of the age. I have read posts that one of the main symptons for ECU was a restriction of engine speed.

 

[anyweb]

could be a duff OVP but seeing as the guy with the problem isn't giving us much details about the actual problem it's hard to tell,

if the immobiliser is not working then you won't be able to drive the car (because you won't be able to START it), so limp mode is nothing to do with this

i agree with what bigasotonuk has said so far

cheers
anyweb

 

[paininthecclass]

Hi,
The immobiliser on this year has nothing to do with the diagnostic side of the vehicle as all it is an aftermarket Scorpion Alarm fitted to the vehicle by MB once it was in the UK.
If it was the Immobiliser at fault the engine would completely die not just go into limp home mode.
If the Immobiliser was at fault the diagnostic would,nt read any codes in the ECU at all as the immobiliser cuts the power supply to it.
I think you have an ECU problem personnally, to be completely honest i don,t think your car will even be equipped with a limp home facility because of the age. I have read posts that one of the main symptons for ECU was a restriction of engine speed.

The car is not equipped with an alarm it is the ecm immobiliser, the ecu was re conditioned last year and the immobiliser is causing the faults the light on the mirror keep flashing, the advanced diagnostics of the carsoft programme plainly said ecm Immobiliser Fault the limp home mode is caused by a relay in the ecm that has picked up a fault cars as old as h reg have this, it shuts down injectors 2 and 3 by stopping the pulse much the same as the immobiliser does.
i am a motorcycle mechanic but not into car electrics at all.

 

[bigasotonuk]

ecm?
The Red and Green L.E.D.s on the mirror are an integral part of the 'standard/factory fit' alarm (and the door/boot L.E.D.s), the only immobiliser fitted to this vehicle was in this alarm system.(flashing green and red L.E.D.s normally indicate flat fob battery)
Why would an intermittent immobiliser cause it to go into limp home mode? The Immobiliser circuit in this car of this age has 'nothing' to do with the diagnostic system. Like i said if the immobiliser was inoperative the diagnostic socket would be dead as the ecu power is the Immobilisation point of the alarm.
What is the exact wording of the fault code reader? As i think it has been misinterpreted.

 

[Autofix]

Hi,

Some 202’s of that era had a transponder immobiliser system fitted. One easy way to tell if this car has it is to look at the surround of the ignition switch. If it has a raised surround to the ignition then it is the transponder type. The raised part is transponder aerial/reader coil.

It is not very clear but the fault appears to be two cyls shutting down. That is not caused by an immobiliser or limp fault. You need to look further for that issue.

The second symptom of the LED’s flashing is connected to the immobiliser but not the way the engine runs. It seems to me that you have two separate faults.

You mentioned carsoft advanced diagnostics. There is nothing advanced about carsoft. I have often seen carsoft lead a mechanic astray. I think you need to look further. The main causes of these going off two cyls are coils, coil wiring, injector wiring and ECU. Never mind the fault codes, get someone with a scope to check what is actually happening.

 

[paininthecclass]

Hi,

Some 202’s of that era had a transponder immobiliser system fitted. One easy way to tell if this car has it is to look at the surround of the ignition switch. If it has a raised surround to the ignition then it is the transponder type. The raised part is transponder aerial/reader coil.

It is not very clear but the fault appears to be two cyls shutting down. That is not caused by an immobiliser or limp fault. You need to look further for that issue.

The second symptom of the LED’s flashing is connected to the immobiliser but not the way the engine runs. It seems to me that you have two separate faults.

You mentioned carsoft advanced diagnostics. There is nothing advanced about carsoft. I have often seen carsoft lead a mechanic astray. I think you need to look further. The main causes of these going off two cyls are coils, coil wiring, injector wiring and ECU. Never mind the fault codes, get someone with a scope to check what is actually happening.

Hi thanks, it is the transponder type, the main module has been tested by lynx and they have told me that it is the immobiliser circuit of the ecm, that is causing the fault, they cannot repair it as something has burnt out, the two cylinder problem has been rectified so just need to short the immobiliser out.

 

[Cosworth]

If you look in the passenger footwell, lift the carpet where the foot rests, remove the metal plate and you will find the imobiliser unit.

I beleive the remote and the unit are coded together.

Have a look and you may be able to by pass it.

 

[paininthecclass]

If you look in the passenger footwell, lift the carpet where the foot rests, remove the metal plate and you will find the imobiliser unit.

I beleive the remote and the unit are coded together.

Have a look and you may be able to by pass it.

Sounds like a plan. what does it look like

 

[Cosworth]

Sounds like a plan. what does it look like

Its a silver coloured unit.

 

[paininthecclass]

there was nothing under the carpet,

 

[bigasotonuk]

Hi,
There should a steel plate bolted down by 3-4 plastic nuts in the passenger footwell,
Remove lower dash panel (phillip scews) pull the top of the carpet back and it will be there (if your car was LHD it would be where the pedals would be) fixed to the floor/firewall.
The ABS computer is there too and is silver also (mine is silver anyway).

 

[paininthecclass]

Hi,
There should a steel plate bolted down by 3-4 plastic nuts in the passenger footwell,
Remove lower dash panel (phillip scews) pull the top of the carpet back and it will be there (if your car was LHD it would be where the pedals would be) fixed to the floor/firewall.
The ABS computer is there too and is silver also (mine is silver anyway).

Hi got it, 2108202226 is that the immobilkiser part number small black box?

 

[bigasotonuk]

Hi,
As i have said i do not have this type of immobiliser system on mine and never heard that this system was fitted to a W202 but this is where my alarm control box is fitted, so i think it would be reasonable to assume that your transponder immobiliser is fitted here.
You could try putting that pt. no. into the Inchcape Mercedes site and it may give you the item description (and price), or alternatively ring your local MB dealer asking for a price for that item ask them the items description.
Just for curiousity how many plugs/cables have you got going to it?
Did you identify the ABS computer in that location?

 

[paininthecclass]

Hi,
As i have said i do not have this type of immobiliser system on mine and never heard that this system was fitted to a W202 but this is where my alarm control box is fitted, so i think it would be reasonable to assume that your transponder immobiliser is fitted here.
You could try putting that pt. no. into the Inchcape Mercedes site and it may give you the item description (and price), or alternatively ring your local MB dealer asking for a price for that item ask them the items description.
Just for curiousity how many plugs/cables have you got going to it?
Did you identify the ABS computer in that location?

the abs computer was not under there, just the body control module and immobiliser, now i just need to find out how to bypass it

 

[Cosworth]

I'm sure if you buy another module and key fob from another car, it would work.

 

[paininthecclass]

I'm sure if you buy another module and key fob from another car, it would work.

everyone is looking at 250+ for modules second hand, the cars not worth that