E39 Driver side rear door lock inoperable

[warsi]

Hi all,
I have a 1998 523iSE (UK) and driver side rear door lock doesn't work using central locking. I can lock/unlock it by push/pulling the lock knob though. It's when I lock/unlock the car then this one lock fails to lock or unlock.

I removed the casing but couldn't see the whole lock assembly due to it hidden behind the corner of metal frame. But I did notice a wire plug hanging on its own, I believe this plug needs to be plugged in there but can't see where without removing the whole lock assembly.

My question is: does this plug definitely needs to be plugged in there somewhere or there's something else wrong with the lock.

thanks,
--

[tAgC]

Had the same problem on my rear driver side door, I had to replace the solenoid in the door as it went bad. Not that bad a job. The solenoid started making a kinda buzzing noise just before it went bad.
There are often loose plugs if you're car doesn't have certain features like lights in the doors etc.
Can you post a picture of the plug might help in identifying it?