Mercedes: 1988 300E Mercedes vacuum lock question, mercedes benz 300e, mb diesel

Question
1988 Mercedes 300E 125k Seattle
I purchased and installed the vacuum unit that locks the fuel filler door.  Unit works fine.  The new unit has only one vacuum line.  But when I lock the drivers door it locks everything but the trunk.  That has to be done manually.  Looking for solution.

Answer
Question:
Does the old fuel filler door lock have two vacuum lines?

The trunk lock issue should be a failed Vacuum Element and/or broken vacuum line.

You need this tool for diagnosis:
mityvac, MB diesel owners hero.
http://www.mercedesshop.com/shopforum/showthread.php?t=102414

There is a small chance your issue may be either the trunk key lock and/or Factory Alarm System.  

Disassembly and cleaning of the key lock is covered here:
Door LOCK issues, link thread.
http://www.mercedesshop.com/shopforum/showthread.php?p=1214456

These issues are near enough to help you.
82 300SD Trunk Won't Open
http://www.mercedesshop.com/shopforum/showthread.php?t=15438

trunk won't open
http://www.mercedesshop.com/shopforum/showthread.php?p=512820

Trunk lock problem-W126 300SD
http://www.mercedesshop.com/shopforum/showthread.php?p=879700


Factory Alarm System Issues
http://www.mercedesshop.com/shopforum/showthread.php?p=1143583


PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1988 Mercedes Benz 300E
Part: Vacuum Element
 Note:  Trunk
When superseding from old part number 000 800 86 75, (1) 202 805 03 44 vacuum adapter and 50mm of 007 997 61 82 vacuum hose are also required.     
O4010-86214 Vacuum Element IN STOCK $55.86  

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=cata...