Hi
The latest on this one is ….. no progress!
I traced signals back through the window lift control module and that was fine, pulled it apart to check for any signs of damage and it was like new inside.
So, armed with the wiring diagram, I traced further upstream to the alarm system control module which lives behind the side panel of the near side back passenger seat.
I removed this and on the circuit board there's a single relay which can be heard to click on the unlock cycle but not a thing on the lock cycle. The alarm sets and unsets so I know this is receiving a signal from the key ok.
My final thought is that the relay on this module isn't switching over on the lock signal. The alarm control unit gives out a signal to set / unset the alarm and on another set of pins, it gives the lock / unlock command to the window lift control unit, which in turn gives the lock / unlock signal to the central door locking command module which sends the relevant signal to the door lock! Talk about complex.
Without access to a replacement alarm control module with paired keys, I'm now stuck.
So, if you are experiencing the same symptoms, I'm sorry to say you've probably got the same issue.
-David-