S40 (New) General : Driver's door won't lock/unlock with keyfob or switch

[Waveslate]

A couple of days ago, the driver's door on my 2005 S40 stopped locking or unlocking with the keyfob or the interior switch. The interesting thing is that the power window on that door operates normally, as does the central locking system (the other three doors lock and unlock just fine with the fob and interior switches). I've ruled out a few possibilities for the issue, after scouring the forums.

Issues (possibly) ruled out:
1. Weak keyfob battery (changed with brand-new one)
2. Weak car battery (reading from lighter gadget says 12.43V)
3. Blown fuse (I removed the fuse and the power window stopped working, as well as all the lights on the switches on the door).

Does anyone have any ideas what the problem might be?

[pinballdave]

If the window is working OK on that door, then the electronics module for the lock/windows is getting power.

It's unlikely to be a communications problem between the door module and the central locking module if the switch on the drivers door operates the central locking on the other doors. (You can confirm the comms are OK by checking if the window controls on the drivers door operate the passenger side windows, as they all operate over the same connection).

So it's most likely to be something in the lock mechanism, either a mechanical problem, a bad actuator motor, or a problem with a microswitch.

[Thassos]

Have you had a look at the connector on the big rubber cable that takes connections from the door to the cem?, it has a rather hard to figure out sliding locking bar that once you know how to release it you see if the pins look corroded or dirty, worth a quick try incase it makes a difference..