Central locking and the soft-close (pull-in) doors and trunk run off vacuum, served by two pumps (a PSE pump under the rear seat and a CA pump in the trunk) plus door actuators that leak with age. Failures are common but often resolved by a fuse reset or actuator/pump replacement, and owners keep spares. …
Vacuum-operated soft-close doors, trunk and central locking
Mercedes-Benz S-Class Coupe / CL (C140) · mechanical