Took car into get inspection for registration. 3rd brake light not working. Ordered light from dealer and asked to have installed (most expensive light I have ever purchased). Technician came back to me, "Not the brake light." All he said, did not bother checking into what is wrong. Another $200 down the drain. Suggestions? Radio and power antenna not working either... Maybe same fuse?

 

The "search' feature is your friend. https://mbworld.org/forums/sl-class-...light-out.html

 

Check the wires going to the third brake light. Mine were broken, where they enter the trunk lid, right next to the hinge.
I soldered them back together, and now it works fine.

 

My car had broken wires for 3d brake light at hinge point in the trunk, cut, splice and solder

 

It was in deed a break in the wire inside the harness at the hinge.