'98 E320 burnt out bulb control unit
 

I still have the burnt out bulb indicater on the dash lite up. I have checked ALL bulbs and they are all lit.
I am thinking it is the control unit that measures the resistance which changes with a burnt out bulb. Anyone know specifically where that control unit is?Think it may be defective.

Are you sure you checked ALL of them?
Licence plate lights, third brake light, high/low beam lights, brakelights, back-up lights ?

Did you check out the tail light assembly that I mentioned in your other post?

It cured the same chronic problem in my mom's '99 E430.

The local Mercedes independent that I mentioned had a stack of defective assemblies in the back of their shop.

The owners of the shop are both former technicians at Penske Mercedes dealer in West Covina, and both techs have attained the Mercedes Master Guild Technician level several times over. It doesn't get any better than that.

They were notified of the problem by their contacts at Penske of the ever increasing problem....