Thanks for your reply.
Where is the J519 / ECM ?
Just the interior lights -
i)the main ceiling lights rear and front (don't come on when door opens),
ii) the LHS & RHS overhead lights controlled by the rocker/individualswitches (don't come on when pressed),
iii) the glove box light,
iv) the lights in the trunk.
There are a number of fuses for the J519 E-box (which is located under the passenger seat, if you slide it back you will see the cover over it)
in fuse box C, left end of dash-
15-7.5a, 25- 25a, 41-20a
Unfortunately, nothing that is shown is directly linked to any of the interior lighting- and since the J519 is a "black box" they don't really give us any information about how any of those fused power inputs affect specific circuits.
You should be able to have that system read with a factory scan tool or Ross-Tech VAG-COM software under address word 09 Central Electrics, and there is also an output diagnostic test that could be run. Without that capability it's a guessing game.