Relay in AW11 Passenger Door

There is a clicking sound in my passenger door when I open and close the driver door, sometimes.  I assume it must be a relay for the power steering or central locking but was wondering if anyone knew what it was before I continue my investigations.  As it is a ventriloquist, I started off thinking it was the alarm system and then the AC system as I have been having problems with those.  However, I have narrowed it down to the passenger door.  I just don't know why it makes such a noise.
 
Any ideas?

Thanks toimr2.
 
With both doors open and the ignition on, if you press the door switch for the interior light on the driver side, a relay in the passenger side clicks on and off twice.  It does not do it when I press the door switch for the light on the passenger side.  Therefore it is not mechanical and it is not related to the light as the light remained on when I had both doors open and was just working the switches.
 
I'm realing starting to think window relay but I find it weird that it is actuated by the driver side door switch.
 
Update: The book shows it to be the Door Lock Control Relay which starts to make some sense.  I'll have to study the circuit diagram to see why I am getting the double clicking.