Join Date: Jun 2014
Could be unrelated... but...
Just went to an Alfa technical day and this issue was brought up, thing is I can't remember which car or the specific system
... Oh hang on, yes I can.
a customer was complaining their battery was running flat in 2 days with car sitting, new battery, there may have been an aftermarket ice invoved...
The tech left the car overnight and first thing in the morning placed his hand on the dash over the tacho, it was hot.
He then explained that all(?) of the wiring runs to the back of the tacho, I guess like a busbar.
A hot tacho means it has short/is faulty. Tacho replaced, no more current draw, no more flat battery.
as you have similar issues and lighting circuits earthing out it may all be related.