I have found this on a quick search.

https://the75andztclub.co.uk/forum/showpost.php?p=2817457&postcount=66

This does not help in the specific case here. But it shows how complex the interaction between the BCU and the ECU can be. The topic starter of the link above has gone crazy as you can see from the number of posts and measurements.

What I just want to say, it might be possible that the BCU doesn't get to sleep in the Morgan Plus 4 because it was programmed for a different body with many more (or different) sensors than a Plus 4 GDI.

'14 4/4 graphite grey