Fiesta Mk6 Central Locking Problem

[mobbsey]

Hi,

I'm new here so I'm not sure if I'm posting in the right place, so I'm sorry if I'm not!

I bought a second-hand 5-door Fiesta mk6 (2005) last week, and it has a very strange problem with the central locking:

• Unlocking the driver's door only unlocks that door
• Unlocking the passenger's door unlocks all the doors (including the driver's)
• Locking the driver's or passenger's doors locks all the doors
• Locking/unlocking either door from the inside has the same effect as locking/unlocking that door from the outside

This is the Finesse model, so it's not remote central locking. I have tried checking fuses etc, but I can't see how it would make sense for it to have blown as it all works fine from the passenger's side. The only thing I can think it might be is if there's some kind of switch in the doors that triggers the central locking, and perhaps this could have come loose or something on the driver's side? If so, where would I find this component? Or do I have the wrong idea altogether?!

Any help would be most appreciated!

Thank you