How To Open 'Locked Out' R129 Trunk Without Damage

[timm9]

In October I purchased a 1998 SL500 and quickly discovered that the battery was draining very quickly from what I eventually discovered was a faulty lower trunk release mechanism. I found a used replacement on eBay and waited for the part to arrive. Last week I replaced the lower trunk release mechanism and stupidly did not ensure the actuating rod was properly engaged before closing the trunk and locked myself completely out.
After searching I quickly discovered that I’m not the first or the last to do this. I was told that I had three (3) Options; 1) Drill through the sheet metal behind the License Plate and then fill with a ‘plug’. 2) Drill out the Locks estimated at $600 to 800. Or, 3) Break out the passenger side tail light.

I’m here to report that I was successful in unlocking the trunk without going through the tail light or doing any other damage whatsoever. Originally I had indicated that I would document the attempt via video. Unfortunately, it went so fast that I never had a chance to video. The ‘unlocking’ part took about 20 minutes and here is what I did/used;

After breaking two old screwdrivers that were obviously tempered I gave up and found a small piece (8 or 9 inches long) of round stock. I heated the round stock and hammered out one end to resemble the blade of a screwdriver. I then bent the round stock in a 90 degree angle at approximately 2 ˝ to 3 inches from the blade end. After removing the right/passenger side license plate light and pulling it to the side, you can then insert the makeshift tool into the recess/opening left by the light fixture. It was a huge help that the ‘broken’ lower release mechanism was nearby as you are flying completely blind and the actuating rod is actually sitting in the way and blocking any possible view of the recessed area that receives the actuating rod into the locking mechanism. Needless to say I will be keeping the makeshift tool inside the car and not in the trunk from now on.

In all seriousness it was not that difficult once I was able to visualize the approximate location of the 'seat for the rod' while holding the old part carefully against the exterior until I had a good reference point. Then you can barely make out a brass colored 'pin' about the size of a 9mm that is part of the actual lower release mechanism. The 'rod seat' is below and slightly towards the front of the car just 'inside' where the actuating rod lies. I realize that 'just inside' may not make sense now, but it will when you are staring into the hole. The other important thing to note is that the mechanism never made a sound. I 'felt' some resistance against the tool and knew I was very close if not right on and reached up and pushed the trunk lid up and it opened. I will post a picture of the 'makeshift tool'. It is nothing but a piece of round stock the diameter of thin screwdriver or small knitting needle with a 90 degree bend and a flat end.

I apologize for 'going on' but I really wanted to document this while it is still fresh in my mind because It's normally me that is desperately searching on a Sunday when everything is closed, and most folks are driving their SL's!

[Gaselec007]

This is fantastic advice and worked supperbly.
A little awkward working blind but saved me a fortune.

You have to remember to keep trying the boot lid as there was no noise when the catch was released.

Mercedes 600sl

[TheSaint]

I know this is an old thread but i have some problems since the trunk lid on my 1992 Mercedes Sl, R129 is stuck in the "trunk lid locked position" and i am not able to turn the key in the thumbler/lock.

Note that it is only the old type mechanical key on my car.

On my car i suppose it is the mechanical lock that is worn because i turned the key to far once this winter and the lock got stuck in the trunk lid locked position.
In that position it is not possible to open the trunk lid using the central locking since i have locked the trunk lid seperate of the doors/other locks.

Right after i managed to turn the key to far to the 15 past o`clock position i tried some lock oil we use in wintertime but it did not help

I pressure washed the car and trunk lid lock and after that i blew out the water and dirt using an air compressor gun.

I have tried a little electro cleaner to lube the lock but i have not managed to open the trunk

I have taken out both the right side and left side license plate lights but i can not see anything where to push or turn to open the trunk lid

That must be the yellow plastic part shown on the picture that you can access thru the left side license plate lamp

Attached is a couple of pictures so please let me know where to put the homemade tool so i can open the trunk on my car

The pic to the left is of the lock on my SL, R129 and the pic in the middle is of the latch and the last pic to the right is of the locking mechanism in the car

I will be happy if any here can help me with this

[TheSaint]

I finally found a picture of where the tool might go on the catch on the trunk lid
You also access this from the right side/passenger side license plate lamp

Is this correct?

[TheSaint]

If you have locked the trunk using the trunk lock and the lock cylinder/thumbler will not turn so you can not unlock the trunk lid

I had a look at how to open the trunk lid today and i got the trunk lid open quite easy

On my 1992 SL, R129 i locked the trunk lid and the lock cylinder/thumbler is stuck or worn so it is impossible to unlock the trunk lid using the key

I took out the right side license plate lamp and placed a small LED flashlight that fit inside the small license plate light opening so i could see the rod go into the lock

Since the rod is in place in the lock (as it is supposed to) it looked tat there where no way i could make a tool to open the trunk lid this way.

But i noticed a little gap on top of the rod where it goes into the lock so i broke a flat screwdriver and welded back together
I though that i might be able to put the screwdriver in the gap where the rod go into the lock

I put the screwdriver inside the opening for the license plate lamp and tried to place the "blade" of the screwdriver on the gap on where the rod goes into the lock which i managed.

Attached is a picture showing how to do this and also a picture of the bent screwdriver with measurement in inches and centimeters

Now i just have to try to repair the trunk lock cylinder/thumbler if it is no all worn out