So... bit of an update, picked up a new CIC screen from ebay as mine was scratched by a previous owner
New screen...
Upon taking apart both screens (as i don't want the outer clear plastic shroud from the new display)... it turns out this screen is from an E60 and has a light sensor on it. Now completely by accident i think i may be able to get the Auto Day/Night setting working on my Nav when i fit the screen with light sensor and re code the Auto mode again.
Only problem is i want my original (E90) non outer clear plastic shroud... maybe time to get modding. Will test first with the E60 shroud before i drill any holes for the light sensor into me E90 shroud.