Several months ago one of the number plate bulbs failed on my 2004 E46 320D Touring. Both number plate holders were fitted with standard festoon bulbs which I replaced with canbus error free LED bulbs. So far so good. At the time I noticed one of the bulb holders was new and the other was badly corroded. The rusted holder I coated with ACF50 protective lubricant which is great at protecting electrics from the dreaded rust!
A few days ago I noted both number plate bulbs were still lit, albeit dimly, after the ignition was switched off and lights turned off. These lights come on (dimly) whether the lights are turned on or not. Incidentally, when the lights are switched on, both bulbs light up fully. They come on dimly when the car is unlocked and locked.
I've removed both bulbs, cleaned and replaced. No change. I then removed the complete bulb holder assembly and inspected the wiring which looks intact. Tried the lights/ignition with the assembly loose - no change. Refitted the assembly and both bulbs still lit dimly. The interesting thing is that both bulbs extinguish after about two minutes - as if they're on a timer.
Any ideas would be gratefully appreciated as a complete new bulb holder assembly from BMW costs around £70 + painting, and I'm not convinced it's the problem!