I noticed recently that when opening any of the doors, only the front interior lights illuminated. The rear lights would illuminate only when the front light was set to be always on using the rocker switch, which is different to other cars and certainly does not seem conventional. I began attempting a repair by checking the wiring to the front light, but all seemed well. I then removed the rear light by gently prising it out, it is held in by 4 spring clips and simply pulls out from the headlining. Again, the wiring to the light seemed fine, leading me to the possibility of the rear light unit itself being faulty.
I examined the joints on the PCB on the back of the unit with a magnifying glass to see a small ring around a soldered joint, which seemed to be a dry joint. I have circled the offending joint on the following photo.
View attachment 17183
To fix this, I heated the joint with a soldering iron and added a little solder. I then put the light back in the car, and it worked exactly as it should. When a door is opened, both the front and rear interior lights now illuminate. I checked our other A2 as well, just out of curiosity, and I found that this rear light was faulty in the same way, and that the exact same solder joint had failed! Both cars had the same problem. I also repaired this, which also now too works perfectly.
I'm not sure if this joint is a known weakness as a forum search revealed nothing, but it's a simple fix if you have a spare 5 minutes!