Very very strange. Any link to what central locking unit you have, as i'm guessing it could be faulty. Have you tried putting the multimeter to the new central locking unit and see if it works correctly? The wiring colours i have given you are correct. Now why the colours change after the door could be a anti theft measure, however alarm fitters would state its true colours.
Try connecting the lock and unlock of the central locking unit to the blue and white in the door to rule out the device being faulty.
Make sure the unit is sending out a negative pulse.
Out of curiosity to you have a third wire for the central locking, as someones alarm or RCL had a third wire for the central locking and the CL only worked when the third wire was connected to the earth.
***********************************************************************
I found this, this is for the right click RCL system....
All the wiring is done around the fuse area by your knee under steering wheel. so undo the cover use your key or a flat head screwdriver.
1st of all you need to cut attach some wires from the control unit to each other.
The yellow needs to be attached to the Yellow/Black(yellow with black line) then the Yellow/Black needs to be attached to the Black like this: -
2nd thing is you need to locate the set of wires coming from the drivers door. they should be at the bottom towards the drivers door.
too check if they are the right set of wires, pull off the rubber covering going from the car into the door and pull the set of wires you think it is. you will obviously see sycronising movement if you have the right wires.
now the wires you need from the control box are: -
-Black
-White
-White/Black (white with black line)
Conect them in this mannor: -
Black - Black
White - White
White/Black - Light Blue
3rd thing is to attack the Red wire to a positive wire. I used the extra fuses at the top. pull out the right set of 3 fuses. and attach to the bottom fuse (when looking at the wires) right wire( as pictured). (it is important that you connect it to the non-fused wire as the red wire has a fuse already.
4th is to wire up so the indicators flash when you lock and unlock the car you will need to remove the housing around the steering wheel its 5 philipshead screws you will need to follow the wires from the indicatorsaround to a suitiable area to do the wiring as the wires are tightly wrapped.
attach the wires in this manor: -
Brown - Light Blue
Brown - Light Blue/Black
it doesnt matter which brown as long as both are attached to diffrent wires.
I came across a problem that after wiring it didnt lock and unlock using the remote. when wiring using the onectors provided or if you are using your won wriggle them about to ensure that the mental from the conectors is touching the metal inside the wires.
if to no avail the conectors from the black box to the wires need wriggling about. if in any trouble post back and i'll try and help you.
Hope this is some use to you.