Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hi, your car uses an electric vacuum pump underneath the rear seat cushion to operate the door locks. First you should remove and inspect fuse 3 and 11 in the trunk fuse box. If the fuses are good just remove and insert them and then try the locks. If none of the locks work I'd say your vacuum pump has gone bad.
Let me know if you have any questions.