Hi Troverman,
I don't know who filled your head with that nonsense about the cruise control "drawing more current if the bulb is out", but it is complete nonsense. The cruise control senses the voltage level at the bulb though a high impedance sensing circuit that cannot draw any significant current at all. If the bulb is out, it draws even less current than normal. (in the range of microamps, not even milliamps!) Manny correctly informed you that the cruise control is connected to the brake lamp circuit on almost ALL cars, not just Mercedes cars! (Some GM vehicles used a separate switch on the brake pedal for a few years) The Mercedes cruise control amplifier has been problematic, but not because of brake light bulbs, instead it has the same problem that all the other circuit boards in the Mercedes cars have - cold solder joints due to the German regulations regarding the non-use of lead in solder. Almost all circuit boards can be effectively repaired by resoldering the connections with a good quality 60-40 solder. I have done several myself.

Regards,
Richard Wooldridge
'82 300D/4.3L V6