Power doorlock problems in w126 - PeachParts Mercedes-Benz Forum

Snibble · #1 03-20-2003, 05:44 PM

I spent some time today trying to figure out why power door locks don't properly function. While examining it today, I found some issues and fixed them. Right now they're better than before, but still not 100%.

Here is what my doorlocks do...

When closing driver side door, all locks close. When opening from driver's door, only the front passenger door opens.

This is better than before when I couldn't open any of the doors or lock any of the doors besides the trunk.

I found today that the Rear Left actuator had a part broken off. The part where the rubber tube connects to the actuator was snapped off. I tried super-glueing the part back, but it was not strong enough. I decided to take a knife and make a hole large enough in the actuator to tightly fit the rubber tube. I managed to do this and super glue around it. Its held securely now.. and after doing this, I have a power door SHUT... but not UNLOCK.

What could be the cause of the rear doors not unlocking? Why is it that when I go to the trunk and lock the trunk, only the front passenger side door locks and the others are unlocked?

Snibble · #2 03-20-2003, 11:07 PM

TTT

Snibble · #3 03-21-2003, 04:53 PM

No one knows? I think it might mean 3 of my actuators are weak or going bad... but not sure.

sixto · #4 03-21-2003, 08:21 PM

Sounds like it. I've never heard of actuators working one way but not the other on these dual action actuators.

Sixto
91 300SE
87 300SDL
83 300SD

Snibble · #5 03-21-2003, 09:20 PM

sixto..

what possible problems could be causing this?
The pump in the trunk? The actuators? or ?

Perhaps a leaking vaccuum line? Where would it most likely be?

I feel that this is a small issue not something big where a new pump needs to be bought. only 1 door is doing its job correctly...

sixto · #6 03-21-2003, 09:49 PM

What I would do is check for vacuum and pressure at all lock positions. If the turnk and filler are working, I'd focus on the doors.

Compare the vacuum and pressure readings at each location. If they're the same, throw some new diaphragms at the bad actuators ($5 each). If they're not the same, then locate and test jucntions.

If one location is working then the pump is low on my list.

Hardly a revelation but that's how I'd do it.

Sixto
91 300SE
87 300SDL
83 300SD

Snibble · #7 03-23-2003, 06:25 PM

I think I am getting closer to the problem...

I removed the driver's door panel and heard a loud hissing sound coming from the actuator. I believe there is something loose or or worn on that one, possibly the reason why its causing my door locks not to function correctly.

Anyways.. i put in my skinny hands in to the door and found electric wires as well as the vacuum line connected to the actuator. I would like to do a further examination of the actuator.. but have no idea of how to remove this particular one. The actuators of the rear doors were an easy pull.. but this front driver's door seems to work in a different way. Anyone willing to help me figure out how to remove the acutator off the door once the 2 brass screws are taken off?

#8 03-23-2003, 09:55 PM

try disconnecting the battery and leaving it overnite for the system to reset, thats what I usually do when mine acts up

Snibble · #9 03-23-2003, 10:02 PM

Quote:

Originally posted by 300SDL
try disconnecting the battery and leaving it overnite for the system to reset, thats what I usually do when mine acts up

Problem is I am 99.9% sure there is something wrong with the actuator on the driver's door. I need to get it out to examine it.. but have no idea how to. I see two brass screws holding it and one screw that holds a plastic piece that appears to be there to protect the actuator. I can't get the acuator off after getting those screws. Its attached to the actual door lock at the top and have no idea what I am supposed to do. I doubt that this is something complicated... because its just a removal of the piece. Can you help? Thanks in advance....

Snibble · #10 03-24-2003, 11:18 AM

TTT

Anyone?

pentoman · #11 03-25-2003, 07:21 AM

snibs

Try closing off the vacuum lines to .. well at first, all the doors, and then try just connecting one door at a time. Alternatively, block off the vacuum lines closer to the pump so you can home in on the problem.

On your drivers door actuator, try monitoring the voltage / resistance on it as you turn the key in the lock (you shouldn't need to remove it). This'll give you an idea wether its working or not.

good luck

Snibble · #12 03-25-2003, 07:11 PM

Hey Russ..

There is something that I need to look at on the actuator. It makes a loud hissing sound where I believe air is leaking out causing the other doors not to function properly. I need to find proper tools to remove my door speakers. Then I wil have more hand room to take out the actuator. I believe that there is a hole in the rubber part of the actuator where it leaks air. When I move it.. it causes a louder hissing sound. I will find time later to take it out.. and find the source of the leak. If it is a hole.. then I hope that some bicycle flat repair kit will take care of the hole.. if it turns out to be a hole. Thanks anyways.

Richard Eldridge · #13 03-25-2003, 10:31 PM

There are two hard plastic lines that carry air from the tank in the trunk. The one with the red stripe closes the door, the one with the green stripe opens it.

I have a manual for a 123, and it says to remove the actuator, remove the two screws and the clip at the top of the rod. Then you rotate it and pull it out.

Your problem is almost certainly where you heard the hissing sound.

There are two types of actuators: the older type can be repaired and is larger. It has two white plastic caps on the top and two more on the bottom.
The newer type can'tr be repaired and has a couple of small hex bolts on the side with the plunger thingie that connects to the door latch.

The older type with the external diaphragms can be repaired. You also might find the leak in the rubber connectors that slide on and off the hard plastic yellow air tubes.

I imagine that your 126 is similar. Good luck.

www.mercesessource.com claims to have repair diaphragms and new actuators for the newer type.

sixto · #14 03-30-2003, 05:03 AM

Snibble,

I don't know if you've figured it out yet. I haven't been into the door lock actuators so I don't know how they're attached, but most of the ACC actuators have a bayonet lock. About 15-degrees of CCW turn (looking at the actuator from the end that doesn't have the rod) does it.

Sixto
91 300SE
87 300SDL
83 300SD