I have an 1995 E420 that has developed a problem with the driver's door lock.

The only problem is that the driver's door will not actually lock. ALL other functions work correctly. This includes locking/unlocking all other doors using the driver's key and/or push button. Additionally, the driver's push button is raised or lowered correctly when any of the locks are activated with the key. But even though the push button is in the lower position, the door itself is not locked. I would have thought that if there was a problem with the driver's door lock that the push button would not operate correctly.

Any ideas?

My 92 400E intermittently does the same thing.

It seems to do it less after I liberally lubricated the latch mechanism.

I will eagerly watch this post in hopes that someone has a straight-forward answer for us!

You lock the car and everything indicates it is locked, but you can pull the door handle and it opens right up. My alarm will sound if I open it while it is locked...

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)

My alarm will also sound if I open the car door when "locked".

I should add that I believe I caused this problem myself. A few days earlier I attempted to lock the car without the keys -- I opened the driver's door and pushed the push button down. It was very difficult to do so (and should have been a warning to me to stop) but it did eventually lock. I have since read in the manual that you should only lock the car this way from inside with the door closed.

I suspect that I bent something by pushing so hard. I'm reluctant to take the door panel off for an exploratory mission so I've made an appointment to have my mechanic take a look. I'll report back with his diagnosis...

My mechanic reported a "bent tab" as the source of the problem. He was able to rebend it which corrected everything. (Sounds like I could have saved $200 if I had explored things myself.)

Perhaps your 400E has a similar problem but of less severity and thus only occurs intermittently?

Thanks for the update. I will open the door panel and look around when I can find the time!

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)

Well, I managed to have a look inside the door panel. After picking up my car, I noticed a distinct rattling sound. It turned out that one of the metal tabs that holds the leather inset had broken. My mechanic fixed the problem and allowed me to observe the procedure.

This also allowed me to query him about the fix to the door lock while he had the panel off. The relevant point is that the door lock mechanism needs to be removed to discover and diagnose the problem. This is because its workings are obscured by the door itself. Without taking it off there's no way to see what the problem is (at least in my case).

I'm in the process of replacing my driver side door and I am taking lots of photos to hopefully post at a later time as a DIY project step-by-step. When finished it should prove helpful to you in your project. I'm actually trying to figure out how to remove the door handle and lock from the replacement door so I can repaint with out them and then switch out for the correctly keyed handle from the existing door. I'll post here once/if I ever get the step-by-step completed.

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Chip Dance

91 300D 2.5 Turbo
93 300D 2.5 Turbo
(Both enjoy Dance-n-Planet Biodiesel)

91 Ford Explorer
(G-wagen wannabe)

I have a 1995 E300D (W124) which had a similar problem to that of the original post. Using the key in the driver door lock would lock all doors except for the driver door. Opening the driver door while all the other doors were locked would set off the alarm. I replaced the vacuum element (actuator) which did not solve the problem. I took out the lock mechanism from the door and upon inspection found that one of the metal linkages was twisted. Straightening the linkage solved the problem. I placed a small black arrow on the offending linkage (click to enlarge the photo). Hope this helps someone in the future.

Attached Thumbnails

 

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1995 E300D

Ok,

My car had (1995 e320) had same lock symptoms on Driver door. The lock tab would go down, but the door would not actually be locked. All other doors would lock and unlock as expected)

I have removed the latch assembly from the door. I see the same sheet metal tab was bent as shown in the image from @williammajor (looks like it is supposed to index into the notch on the mating sheet metal part). I used needle nose pliers to bend it back to where it indexes squarely in the mating part's notch. Now, I cannot - with my fingers (w/o fear of applying so much force that the other sheet metal bracket might bend) toggle the lock linkages to the locked position. Is that normal? I would think that the toggling of the latch to lock/unlock positions should be easily achieved. Does the pneumatic actuator really apply an incredible amount of force? Or do i have binding somewhere else in the latch?

I do not want to put this all back in the door without some indication that the latch is "normal/good." My gut tells my my latch is bound up and probably needs to be replaced. I would like to get my car back together however.