I've read some previous posts about this, but I haven't quite been
able to piece them together.
I have a 380SE (1984). (I love it). However, all of a sudden, I
could not open the trunk.
For a while, I have not been able to open it manually (a few weeks).
Now, all of a sudden, I also cannot open it through the central
I have not yet tried to investigate vacuum issues, but will. My
question now is wht might make the manual method not unlock the trunk?
(Quarter turn to the left doesn't seem to work)
I had this problem on my 84 500SEL when I got it. I think the 84 380SE will
be the same.It seems that the trunk is locked electrically by the alarm
system if it has one. There should be a cable inside the car close to the
left rear door (I say Should be because I never found one in my car) that
you pull and have someone else push the botton on the trunk and it will
open. Also try unlocking the doors with the key. Try both front doors as
both have the switch in them to unlock the trunk. On my car, vacumn has
nothing to do with the trunk lock.
Hope this helps.
MBs come with two keys, a Master Key and a Valet Key. You might be trying
to open the manually locked trunk with a Valet Key, after it's been locked
with the Master Key.
If you share the car with another driver, maybe you each are using different
types of keys. If the other driver (with the Master Key) manually locked
the trunk, and you are using the Valet Key for regular use, then your Valet
Key won't open the manually locked trunk. Only the Master Key will.
The Valet Key will unlock the doors, fuel flap and start the car, but won't
give access to a manually locked glove compartment or manually locked trunk.
The Valet Key will turn in the lock when trying open the trunk, but won't
open it. It has to be manually unlocked with the Master Key.
Just to make sure there isn't some confusion about using the wrong type of
key, I'd suggest finding the Master Key and see if that will manually unlock
Heh heh... This is because of your alarm system... factory alarm system.
What you have to do is make sure the factory alarm is still hooked up...
located underneath the front passenger floor... plastic floor and there is a
Then lock the car as usual with your master key on driver door... maybe the
passenger door will do also... use that square handle one... lock it and
then unlock it... and see if your trunk can be opened.
If yes, then immediately disconnect the alarm unit... they do go haywired...
Make sure you keyhole for the trunk lock is vertical position.
Ah-ha! Thanks Tiger, I'm going to check it out on my 84 300SD.
I have the same sort of problem. My solution was to wail on the lock
button with my thumb until it (the trunk lock) surrendered. Once
unlocked, it works fine. It needs a reminder once in awhile (but my
thumb has time to heal in between training sessions!).
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