Brian, I'm starting to think the same!
Jochen, thanks for your help!
Okay, downloaded the latest (beta) navcoder.
select Code/Telephone
Click on 'Read ID'
Populates the data on top 2 lines, everything else blank.
click on 'Read TCU'
The bluetooth box is Ticked.
Everything else in the bluetoth section is blank.
VR section remains greyed out.
SDV section is active, but blank unless I click on SDV defaults
'code TCU' remains greyed out.
Even if I populate all the blank fields on the page, the 'code TCU' remains blank.

Jochen, how do I get a log of the TCU coding?

Many thanks for all your help everyone!
Stringbag