Wheres the pump/relay or whatever for the door locks located....mine are working only about 75% of the time. Also would a clean up fix this issue?

Sorry for the new guy questions...I did a search on this but couldent find my answer.

Thanks
Robert

The locks run off vacuum that is produced by the vacuum pump on the engine. There is a black "egg crate" looking resevoir in the trunk under the rear shelf.

You have a leak in the system if the locks dont work. A leak anywhere in the system can cause havock in the rest of the system.
Check here for troubleshooting basics.

http://dieselgiant.com/mercedesvacuumtroubleshooting.htm

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