I would first pull the cowling in the trunk to gain access to the bulbs, check all of them (some are double filament) including the bulb sockets especially the brake sockets and bulbs. If you find rust build-up you may be able to use a wire bottle brush or sandpaper to get a better connection.I drive a 2000 C230. When I turn on the headlights or use the left
turn signal the Cruise Control disengages. Any help would be appreciated.