
At the moment, I have all the buttons, relays and rear-left winder.
The most interesting will be to find points "9/B4", "9/B1" and "13/A2", to which the relay 810 and backlight connect to.
Are S1 and S2 harnesses the same?
I've not checked, but iirc, the relay plugs into the main fues/relay board and the connections are from that board and behind the radio, as said by citroenxm.
Buttons are the same, for sure. The difference might be in motor connectors, as S2 and S1 motors are different.