I've done a whole load more testing on my set up and it seems things are mostly working as they should, apart from the actual level of voltage to the cup light. Its only 0.65v when the lights are on, when I think it should be 12v. Turn the lights off and the 0.65V decreases to zero as one might expect.
I've even run a second pair of wires and tried different earthing points to check its not the wiring and I get the same results regardless. I'm therefore still leaning to a coding issue which might send a higher voltage through the circuit. So before I give up and wire to the ciggy lighter, I'd love to understand the adaption channels to make sure it's not something simple. Its pretty complex though and there is a challenge to understand which of the many adaption channels might relate to the cupholder wiring. Therefore it would be really helpful if someone with the ILP already fitted could share a BCM adaption map they might have please.
Failing that it would be useful to know which lights are controlled by the "front" background lighting setting in the MMI, and so if there is anyone with ILP fitted who could confirm that, I'd also be most grateful.
I'm sure this info will ultimately be useful for others retrofitting ILP, so any help gratefully received.
Thanks in advance
Adam