Immobiliser, Central locking and IR key problems

[maxicab]

Hi all,
I posted this problem earlier on the end of an older post, but have had no bites, so I'm hoping that starting a new thread may be a better idea. Can anyone please advise on the possibility of immobiliser bypass or removal or swapping or any other options for W124s? I think that it may be the best solution for my problem (a UK 1994 A124 Cabriolet with 880 and 551 codes). It has the green/red LEDs in the drivers door lock and boot lock, both of which are only very occasionally responding correctly to either of the original 2 key fobs - which as best as I can tell are working OK and have had new batteries fitted. I've tried a variety of synchronisation processes but nothing has changed. So the car usually doesn't unlock with the IR remotes. Of course I can still enter the car via the keylock in the passenger door, but then I can't start the engine as the immobiliser will not be deactivated. The dashboard lights all come on and starter motor spins nicely. If I am manage to flukily get a door sensor to respond I can get it started, but I'm too concerned to drive the car very far and stop or park it anywhere as the likelihood is very high that I won't be able to start it again!
If immobiliser removal or bypass is not feasible (seems that this may be the case with a factory immobiliser, which I think this one may be), (how can you tell?), and I have to work on repairing the unlocking, it seems unlikely to be a door sensor problem since both sensors are acting up similarly, but is there a downstream signal amplifier to which the two door sensors feed before sending signals to the central locking, immobiliser and alarm modules? I haven't yet found any of these modules but think the immobiliser module is under the rear seat and the alarm has a ?K37 relay behind the dashboard. Does this all sound correct? Where is the central locking module/pump located?
Is there any chance that both the key signals are simply too weak, and that a new key from the main dealer would sort out all the problems? I have been told that these single button IR keys are no longer available from MB, but does anyone know better? People seem to have been able to buy them until around 2020.

Thanks, David

 

[Toby Banks]

Have you tested the infra red is working? Just look at the end of the key with your phone camera and press the button. If its working , then you should see a purpleish light at the end of the key when viewed on your phone. If its not working then speak to Paul Young at www.remotekeyrepairs.com . I had similar issues with my remote key doing all sorts of strange things ( generally not unlocking/locking ) and he has managed to sort them . He charges £60 and will give a full refund if he cannot fix them.
Toby

 

[maxicab]

Thanks Toby, yes the keys both glow and/or flash with a purple light when viewed through the phone camera. Does your key glow continuously when the button is pressed, or does it send purple flashes? It is certainly possible, but it seems a little unlikely that both fobs are not working, but thanks very much for the details about Paul Young which seems to be a great discovery. I have sent him a message and will probably get one of my keys revamped. If that then works, then I will get the other done.