Hi again,

I can feel your frustration. Shorts are sometimes hard to find.
Electric illumination is the lighting behind the instrument panel, the dimmer to regulate the instrument lights etc.

I looked at my Hayes electrical manual and it stated that a drain of .5 amps is probably excessive and will drain a battery.
Now you know already the fuse, that is suspect.
I would want to have an instrument that can read that drain in that general magnitude. So setting my multimeter to mA should give me something like 500 or more on the scale, i.e. 500mA = .5A. I don't think uA is the right setting.
I connect my multimeter between the negative battery cable and the negative battery pole and see what I read. You need to read something at that spot that makes sense to you like more than 500 mA.
Now I remove the fuse and that number should be close to Zero.
Then you proceed as Gilly has suggested, i.e disconnect all at the powerside of the fuse box and put them back on one at a time and measure their power draw. Again, it should be in the mAs and one of them should stand out and being close to the total draw measured at the beginning.
As Gilly said, that one you leave off, start the car and see what is not working. Then you follow that circuit.

If the drain stops when you disconnect that fuse, it has to be on that circuit.
Good luck

__________________
Reinhard Kreutzer
1987 420 SEL (126)