ive had a bit of a nightmare with my astra mk4 electrics recently, the lights in my clocks stopped working, so did the centre console lights, heater switch bulbs etc. also my rear fogs stopped working but ive managed to sort them now, it was the block not pushed in place onto the back of the light switch unit. as for trying to find the cause of the dash lights not working, i dont have a clue. now... ive tried another 2 sets of clocks, another couple of light switch units and checked all the fuses, checked the plug on the back of the heater control unit but just cant find anything. now, when i switch the lights on, the bulbs in the light switch unit light up (headlight adjustment and the sliding dimmer dial) but nothing else. the light dimmer wont work, the light switch unit stays on full brightness where as when all the lights are working even the light switch unit dims also. all the other lights work on the dash, indicators, oil light, fog indicator etc. i have tried checking the connector that goes into the back of the speedo dials with a multimeter to check every terminal with the lights on and off but i dont see any voltage change on any terminal so that to me indicates there is no live getting to the dash bulbs at all.
sorry for the massive explination but i thought its best to let you know what ive tried so far,
any info is much appreciated,