Here is the description of my problem occurring on my Skoda Fabia 1.4 MPI car, built in 2003:
The green dashboard cluster illumination (that illuminates the speedo, rev counter, time and miles) is fully illuminated when I turn the lights on while not in ignition.
The green dashboard cluster illumination becomes very dim (but stays on) when I turn on the ignition, or start the car.
Dashboard warning lights (ie: battery indicator) work perfectly.
Almost none of the cockpit guidance lights work (ie: charger, temperature control dials, electric windows). The notable exception is that the guidance light on the light switch dial (next to the dimmer) does work.
The light dimmer has no effect whatsoever on anything.
My external lights seem to work fine always, as do the curtesy internal lights (ie: the bright white light above the centre console, and the bright white light in the boot).
However, the festoon-based number plate lights at the back of my car do not work, at all.
Based on the above, does anyone have any idea whatsoever as to how I could solve this problem? I wonder if it is the reason why I've recently had to purchase a new battery despite the fact that I had already bought and installed one myself half a year ago.
Here's a bonus oddity: If I turn the lights on without ignition, and someone closes or opens a door, then the green dashboard cluster illumination temporarily dims and then, after half a second, returns to being fully illuminated.
Any advice is much appreciated!