Trunk lock doesn't open on '84 300 SD and alarm activating

I recently have had the onset of the trunk not unlocking with the door keys when I unlock the driver's door. Eventually, it did open after jostling with the trunk lid for awhile, and I placed some stuff in the
trunk that I need to access NOW. So, the keys that I have for the auto do not unlock the trunk but the trunk locked with the door key. I don't know if the keys I have are valet keys (they look original with one having red plastic elevated knobs on either side below the key ring hole). I actually have the car at a paint and body shop and they are trying to access the side moulding in the trunk. When I returned there today with the other key, the alarm activated when I opened the unlocked passenger door, and it continues to go off after I try to get in the trunk with either of my keys when I open the driver's door again. Can anyone shed any light on this?
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My 1984 300SD has a factory alarm that includes an extra electrical lock in the trunk in addition to the vacuum lock. When the alarm is set, this lock is set. Sometimes low battery power or a sticky electric motor on it prevents the trunk from opening, even though the other locks are "off". Try making sure you have a full battery charge and have some one work the driver's side lock while you listen at the trunk for a "wrrrr" sound; then open it. Once open, disconnect the two prong electrical connection to the little worm gear motor at the trunk lock, so it won't happen again. Good luck. Mine eventually opens after a lot of trying.
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And if you still cannot get the trunk open: Remove the rear seat bottom and look on the drivers side floor. You will find a pull loop attached to a cable. Have someone pull on this as you stick the key in the trunk lock, turn it to the left, and then push it in. The trunk should now open. The factory put a manual override in for this reason.

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I would try with driver door... with square key handle to lock and unlock to try to disarm the alarm... Make sure your trunk keyhole is in horizontal position...
Once you got your trunk free... go to front passenger seat floor mat and under that black plastic floor... there is the alarm unit... unplug it and tape up the wiring harness
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Your alarm is screwed up... very common. Once alarm goes off, the trunk will lock indefinitely until you properly unlock the car... by the driver door.
The key you got is the right key... master... the valet key has ovalish handle. Try unlocking the car a couple of times from the driver door... Make sure the trunk key hole is in vertical position.
Lastly, once you unlock the car and trunk, disconnect the alarm unit and tape up the wiring harness... located under the front passenger seat side under the carpet where your feet rest... it is under that black plastic false floor.
If you cannot unlock the trunk, try disconnecting the alarm unit to see if it will let you gain access.
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somebody tried the fork approach on my 280SE but did not get far. what I learned is that the door connectors are easily adustable back to the right position from the inside.
have a look:
http://www.flickr.com/photos/raudzeppelin/157387230/in/set-72057594138495302 /
N
snipped-for-privacy@gmail.com wrote:

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OOOPSSSSSSSSS. I'm sorry about that fork approach, but it might be my next recourse. I have done everything suggested in this and previous posts except work on the actuators, because I seem to have the air supply to lock the thing. Anyway, originally, the lock was so stuck in horizontal position that it took vice grips on the Mercedes key to eventually get it to the left vertical position which I think is the correct position to open it with key. I had attempted that before my post and that didn't unlock it. Today I disconnected the alarm after taking the the back seat to unsuccessfully attempt to find that elusive emergency release cable that I had looked before after reading older posts. There aint't none there!!! Or, if so, please be a little more descriptive in where exactly to find it. So, in the process of having a friend jiggle the trunk with the alarm unhooked, I eventually ended up breaking off the key in the lock. I have seen another post asking about the plastic round inserts in the metal between the trunk and the cabin of the sedan. I could not pop one of these out, and figured if I did, I would have to cut through the trunk liner to reach into the trunk to remove what I could through the hole. This is not going to get me access to the spare tire and jack if I ever eventually need them. Thank goodness the fuel door still opens. Please give me some more direction. I am living in Mexico and there is no Mercedes garage within hundreds of miles. I brought this diesel down here because I thought it was bullet proof. Niels wrote:

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