W202 1994 C280 Scorpion Immobiliser Stuck On

[scott79]

Hello everyone, I have a 1994 C280 Sport Saloon. I left it unused for a couple of months (locked & armed) then the alarm siren started to sound quietly (due to the battery going flat, not because it had been set off).

At this point neither of my fobs would work (either for central locking or for disabling the immobiliser) so I turned off the alarm siren under the bonnet with the small round key. I then recharged the car battery and turned the alarm siren back on with the key (it did not sound as the battery was now charged).

I tried both fobs again but they failed to work for either the central locking or the immobiliser. I read in the manual that if the battery goes flat you will probably have to re-sync the fobs. I have tried doing this as per the instructions but to no avail. I have tried replacing the batteries in both fobs and tried the re-sync process again but to no avail.

Strangely though during all my messing about the alarm has never sounded nor have the indicators flashed etc, perhaps the alarm was not actually activated only the immobiliser??? Anyhow, my problem is that the immobiliser is still active and I can not start the car!

I have the dealer fitted scorpion alarm / immobiliser with the seperate rectangular fobs, the keys are the old basic type with the carbon fibre style black plastic like those of a 190E.

I also have on the dash to the right of the glove box a red led which is always on. It do not have a seperate switch / key for turning off the actual alarm immobiliser as is suggested I may have in the manual.

When I have sat in the car messing around trying to get it working I have noticed that I can hear a clicking on & off for a period of time, then the clicking stops for a few seconds, then it starts again.

Can anyone help me with this please, how can I get the fobs to work again or even just disable the immobiliser as I just want to get the car on the road again, theft security is not a concern now with the car being this old.

Thanks, Scott.

 

[Alex Crow]

i suggest removing the entire system, i have done many of these for exactly these problems.

 

[scott79]

Hi Alex, is this a feasible DIY task, something any auto electrician would be able to come out and do or is it a more specialist job ? Thanks, Scott.

 

[Dec]

Can you do a test on the key Scott.

Dec

 

[scott79]

Hi Dec, I have the standard 190E type keys not the flip out type you show here, both my scorpion fobs seem to be ok though (these are for the central locking, alarm & immobiliser combined) - the red light shows when pressing the button, I replaced the batteries in both anyway just in case, both worked fine before I left the car parked up.

 

[Dec]

Will the key fob lock/unlock the doors every time, the Red light on the dash means the alarm hasn’t disarmed so neither has the imobeliser.

Dec

 

[scott79]

No neither of the fobs will operate the central locking, I have to use the key (previously they both worked the central locking).

 

[Alex Crow]

Hi Alex, is this a feasible DIY task, something any auto electrician would be able to come out and do or is it a more specialist job ? Thanks, Scott.

any auto electrician should be well up to this task, and a competent DIYer will be able to do it as well. it is really just a job of following the wires and removing/making good.

 

[Dec]

One theory for you, if the battery is disconnect then the alarm thinks it is being tampered with so it will arm itself the moment the battery is reconnected, a flat battery could also make the alarm think it is being tampered with so it keeps arming itself no mater how many times you try to disarm it.

Now for this theory to work you would need to have a flat battery or one in very poor condition, try, if you have one, a battery charger for an hour and try again.

There may be a depleted rechargeable battery inside the siren IF there are more than 2 wires going into the siren.

Dec

 

[Alex Crow]

dec may well be right - there has been a recent and very good thread on replacing these siren batteries. also the alarm systems are still available new for fairly little cost.

but the hassle of a car that cannot be trusted is why most prefer to pay around £50 to £75 to have them fully removed and the original wiring repaired.

 

[Dec]

Alex, if a battery was in poor condition and was left in a car for two months would it ever recover and become fit again, this could explain why the central locking is not working.

Scott, what are the dash lights and the heater blower doing when you turn on ignition?

Dec

 

[mutant hifi]

94 c220 electric gremlins

I just had a similar problem today - red light on dash stuck on, scorpion key fob wont operate doors, old 190 type key. car starts ok. it worked (unlocked doors), then as i turned the key in the ignition all the power went dead. I diconnected and reconnected the battery and the car would start but the red light still on and now my fob won't work.

my heater dash lights have been flashing for a while now when headlights off and recirc doesn't work. last time i disconnected the battery the heater panel worked for a while.

can you guys help with my gremlin??????

 

[scott79]

My local auto electrician came out and disabled the alarm / immobiliser for £40 Car now starting but I don't have the remote locking functionality - there must be some combined circutry with the alarm/imobiliser/remote locking, i'm not fussed though!

mutant - i guess your alarm/immobiliser are off 7 you can start the car ? if the fob has stopped working have you tried re-synching it as per the manual ?

 

[Dec]

Hifi, the Red LED on the dash means the alarm hasn’t disarmed, when you unlock, the alarm is also disarmed, check out the Scorpion fob, in particular the battery connection and the tactile switch for broken solder joints.
http://forums.mercedesclub.org.uk/showthread.php?t=48718


Dec