Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
The feeds for the lights are unfused from the rear SAM unit
This is a common problem on the E Class & is almost certainly down to broken wires to the boot lid
The wires run along the left hand boot hinge - you will need to remove the plastic cover from the hinge & inspect the wiring.
If broken then new lengths of wire will need to be soldered in to repair the wiring loom.
I have seen this problem many times before on the W211 E Class
Best regards, Paul