Mercedes-Benz 300 SD 1978, Owner'S Manual

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Keys Doors
Master Lock System
The m aster lock system sim u lta n e ­
ously locks or unlocks to g e th e r with
the d riv e r’s d o o r all o th e r doors, fuel
tank fille r flap and tru n k lid. As the
d riv e r’s d o o r p lunger is m oved, the
plungers of all o ther do o rs m ust move
at the same tim e. If this is not the
case, the lock of the co rre sp o nd in g
door has not engaged fully. Open the
door once m ore and close it c o r­
rectly.
W hen the m aster lock system has
been applied, the lock plungers of the
fro n t passenger d o o r and the rear
doors can also be operated m anually
from inside. In ad d ition to this, the
front passenger do o r can be locked or
unlocked by means of the key.
The m aster lock system can only be
applied by depressing the p lunger on
the driv e r’s door. Lock plungers of the
other doors cannot be depressed
individually.
The tru n k lid can also be unlocked
separately by tu rn in g m aster key
clockw ise to the stop. Push the trunk
lock button in w ith it and lift the lid.
Return the key to its initial position
and w ith d ra w it. To lock the lid, close it
firm ly. It will then be locked again by
the m aster lock system.
A p rovision has been m ade to
fa cilita te p e rm a n en t locking of the
tru n k lid fo r positive prevention of
access to tru n k by unauthorized
persons.
Before leaving vehicle with an
a ttendant, lock tru n k with m aster key
(square head) by tu rn in g key
clockw ise to stop (tu m b le r slot
vertical), then p ro vid e a tte n d a n t with
rou n d -he a d e d su p p lem e n ta ry key.
Thus, the tru n k lock has been
excluded fro m the o peration of the
m aster lock system and ca n n o t be
opened e xcept with the sq u a re ­
headed m aster key.
To reverse this, turn tru n k lock
c o u n te rclo ckw ise back to horizontal
position of the tu m b le r slot with
m aster key. Lock w ill then be
reengaged in m aster lock system; that
is, it w ill a u to m a tica lly be locked or
unlocked depen d in g on w hether the
d riv e r’s d o o r is locked or unlocked.
The m aster lock system operates on
vacuum generated by the engine. A
re se rvo ir allow s the m aster lock
system to be actuated ab o u t five tim es
a fter the engine is turn e d off. If the
system can then no longer be
engaged, idle engine fo r a short
period.
If no vacuum is available, doors and
tru n k have to be locked ind ivid u a lly in
the norm al m anner. T h e fu e l tank fille r
flap, however, rem ains unlocked.
Note:
If the fille r flap cannot be opened
when the m aster lock system is
unlocked, refer to “ U nlocking of the
Filler F lap” .