Trunk lock problem
 

My car's trunk lock hasn't worked since before I owned it. Today I was messing with the vacuum locking system (which I will put another post out asking for help with) but in the process I used my mitivac to look for leaks and I inadvertently locked my trunk (with the vacuum from the mitivac) and the gas tank. I then shut the trunk lid unknowingly. Keep in mind, my vacuum pump is disconnected.

My trunk will not open with any of the keys I have (and never would). So now I cannot get into the trunk or into my diesel tank. I am hopeful that the lock can be picked by me (and I am inexperienced at such things) or by a lock smith. Does anyone have any suggestions on how to proceed to open my trunk :confused: ?

Thanks.

Dan '84 300 SD

A locksmith is your best bet. The fuel tank is in the way of crawling in from the cabin.

Sixto
... stay tuned

You don't say what your car is, but 300D's have an emergency pull wire under the rear seat to unlock the truck. Just pop out your rear seat and on the driver's side you will see a metal wire running from the trucnk...hold off on that locksmith until you check this.

[QUOTE=Slcom1983;1245722]300D's have an emergency pull wire under the rear seat to unlock the truck.

Really??, thats news too me.

danny
You tried applying vacuum to the "unlock" vacuum line that runs to the trunk, yes? (none to the tank flap)

Dan,

I may have the same problem with my 240D (except it is not locked yet).

None of the keys will even go all the way in the trunk or glove box locks.

What I found the problem to be is I only have Valet keys. Even the square headed one is a Valet key with a replacement plastic head. What I need to do is get a proper blank and cut the new blank from the best working key that I have. By the way, I had the dealer cut new keys and the new keys wouldn't work in ANY of the locks.

I know this is not an answer, at least not to all of your trunk lock problems but.... even with a properly operating vacuum/lock system you can get nailed with "OS, cant open the trunk" Something like this..car is all locked, you go back to get something outa the trunk, opening it with the key, cant remember the exact sequence from there but I remember trying to open the trunk for 10 minutes in a hot parking lot. I open the trunk using the "central" system now. Point is after fooling with the system this "sequence" might be hindering you too. You should be able to "over ride" the vacuum system. At least if you have the right key:)

I have another theory (which I think happed to me). Both of my keys are square and should be master keys, but one fits the ignition and the other the truck/glovebox. I believe that the PO had a new ignition switch put in and with it a new key. However, since the trunk and glove box lock weren't changed out....voila! now you have 2 master keys that aren't "masters".

If vacuum in the "unlock" line does not work, try a little pressure in the "lock circuit."

trunk follow up
 

Thanks for all of your input. I will remove the back seat and look for the wire. Since I have a 300 SD and not a 300 D it may not be there, but its worth a look.

Steve, in answer to your question, I pulled the vacuum lines from the 4-way rubber connector in the trunk of my car. That way I could look at where there might be leaks. One line went to the trunk lock. That one held a vacuum great (and it locked the trunk:( ), another went to the diesel tank lid (which also seemed to hold a vacuum and locked, although I may have locked that manually by pulling on a little latch in the trunk), a third went forward to the rear passenger door area (and did not seem to hold a vacuum - how to find that leak was going to be my question before all this happened) and the 4th went to the vacuum pump.

My auxiliary (trunk) vacuum pump is 'new.' A friend from this site sent it to me and it seemed to pump fine at first a few weeks ago when I installed it (although my central locking system still did nothing). Yesterday the pump did nothing, so I am concerned that I may have burned it out from overwork if it was trying to pump and I had a vacuum line pulled so it was just loose. Anyone know about that?

Anyway, first things first, I will look for the magic wire under the passenger seat. I'll also make sure that none of my keys work (a person at a local shop had a new one from Mercedes made after I bought the car - thought I tested it, but ....). Failing that I may have to bring the car to a locksmith (while I have enough diesel and WVO in the tanks, that is).

I'll report back on this saga and then I can get back to what my original questions were.

Dan '84 300 SD

lock circuit
 

I only saw 1 vacuum line going to the trunk lock area, so I am in the dark about how the vacuum lock and unlock circuits work and whether my car still has both. It certainly seemed to have a vacuum 'lock' though...

I have an 84 SD also.

There is an electric part to the system that unlocks when the drivers door is unlocked with the key.

Then, you push the key into the trunk lock, turn it to the left, hold it in that position and push the button.

Works for mine.....my central system went crazy when my wheelwell flooded...just sits there locking and unlocking the locks until the battery runs down.

Give that a try.

I second what Fuzzball says. My 84 500SEL doesn't have a vacuum lock on the trunk as far as I know. It is locked by an electric actuator operated by the alarm system under the passenger foot rest. When I first got my car, I knew less about MB'S then I did about women which is nothing. On one of these cars, if you lock the car from the drivers or passengers side, the trunk locks and no number of keys will get it open. My owners manual also says there is a cable under the rear seat but I have never been able to find it. Try unlocking the drivers door with the key and then try the passenger side. May also help to tap on the passenger side foot rest, or toe board or what ever it is called , with something. If it is a bad solder joint in the alarm controler it may help. The above is just food for thought.

Don't believe that all of the 300D's have the pull wire to open the trunk, our '83 does not have it. The ones that do are those that have the alarm system, in case it malfunctions. Not sure what years had the alarm system, but the '85 parts car definitely has the pull wire and it has an alarm system also.

trunk lock problem ct'd - rear pull wire
 

Slcom83, you are right! To my surprise, underneath the rear passenger seat is a bundle of wires and vacuum lines and amongst them is a pull wire (within what looks like a vacuum line). The pull wire comes out into a tidy loop with these words written on it on an old label (in German) "Kofferraum-entriegelung." I went to the online translator to find out that that means "Trunk Unblocking." That sounds like great news.

Only problem is, when I try to pull the wire nothing happens except it seems to cut into my hand :( . Is the solution to this just more force, or is there a way to pull these pull wires that doesn't risk snapping something?

In answer to others' suggestions, neither of my Master keys seem to work in the trunk, although they do in the glove box....

The way mine worked was the wire had to be pulled while someone else pushed in the button and opened the trunk. Just pulling the wire did not "pop" the truck but holding in the wire allowed it to be opened by someone else. However, mine did have the alarm system and so yours may not work this way.
Stan