Re: Bulb failure warning light - but all lights are working!
This will not help you much, but my 156 had a barely noticible illumination on the o/s rear tail light, bulb light on the dash, all voltage/earths checked out.
Ended up running a feed from the n/s rear tail lamp to feed the o/s rear and provide proper illumination.
Put it down to cr*p alfa electrics and tollerate the bulb failure light on the dash along with the airbag failure light - another typical alfa fault.
I learnt to enjoy the alfa driving expereience and learn to live with the fact that...
when these things go wrong you will end up remortgaging your house and putting your wife out on the street to pay for the repairs, then praying to God that you can live the rest of your life and run your car for a handfull of halfpenny bits.