Simon,
One VIS motor is currently away at Stocktake's for repair so I've not been able to try out the diode yet. It's connected and awaiting the test though.
Do you know the reason why the ECU doesn't like sharing the same switch with the interface? I'd like to understand it.
I've reassembled the car's interior and apart from the radio still being out to let me finalise the switching, it looks tidy again.
Dougie.