C CLASS IMOBILISER

[merc engineer]

Hi Can anyone tell me how i can dissarm the imobiliser on my 220 diesel
It is a 1996 model.. It is on its third mirror since new .All i want to do now is disconect the imobiliser.what wires do i disconnect and where are they located.help....

 

[Arnie]

It depends on what alarm system you have. Generally, the main immobiliser is part of the ignition system which reads the code in your ignition key and this should not be removed as it links with the Engine Control Unit.

Additionally, the alarm unit may immobilise an additional secondary circuit such as the Fuel Pump (two circuits required for Thatcham Cat-1). However, as to where and how this is spliced into the car's wiring, you will have to trace the wires to find out. This is because UK MB dealers fitted OEM Scorpion alarm systems and the alarms were not factory standard. Each dealer will have had slightly different wiring methods.

Look under the dash or in the engine-bay for the Alarm controller unit and then trace the wires back from there. Yes it's laborious and will involve removing many panels.

 

[merc engineer]

It depends on what alarm system you have. Generally, the main immobiliser is part of the ignition system which reads the code in your ignition key and this should not be removed as it links with the Engine Control Unit.

Additionally, the alarm unit may immobilise an additional secondary circuit such as the Fuel Pump (two circuits required for Thatcham Cat-1). However, as to where and how this is spliced into the car's wiring, you will have to trace the wires to find out. This is because UK MB dealers fitted OEM Scorpion alarm systems and the alarms were not factory standard. Each dealer will have had slightly different wiring methods.

Look under the dash or in the engine-bay for the Alarm controller unit and then trace the wires back from there. Yes it's laborious and will involve removing many panels.

Thank's Arnie. The alarm unit is fitted in the passenger footwell ..It is as you say an aftermarket unit. I have traced all wires from it and none of them work the imobiliser.The siren is under the bonnet and has a key to turn off the siren.It is very annoying when you come back to the car and it is a gamble to see if it will start or not ..All the lights on dash come on and engine turns but will not fire.

 

[190]

This is the best place to fit a merc immobiliser.

 

[Arnie]

Well, if you are sure that the alarm is only just that, without an additional immobiliser, it seems then, that the only other possible immobiliser is the ignition-key one. If it has this, the ignition-key lock will be surrounded by a raised collar, which is the transponder for the key. Behind the dash, this will connect to an interface unit (usually siemens), which then connects to the ECU. Check this wiring, but it could be a faulty unit. Unfortunately, this immobiliser cannot be "disconnected".

Otherwise, you have some other non-related problem... :?

 

[merc engineer]

OK i will have a look at that . Thank's for your help.[Arnie]

 

[merc engineer]

This is the best place to fit a merc immobiliser.

If you can find it 190 you are welcome to flush it away

[/quote]

[/quote].