balthus

On Saturday I went to open rear driver door and it would not. Tried locking/unlocking with fob a few times. Tried from in side - nothing. Came home and a few hours later, my husband gave it a try & it opened! But yesterday, it did not.

Although my car only has 23,000 miles, MB warranty ran out last month & I did not purchase extended warranty from MB.

Is there anything else we can try before taking it into dealer?

Do you think they may cut me any slack with the repair?

And, any thoughts on what is wrong & how big a job this may be.

We are moving in a few weeks & I really need to be able to be able to use this door.

Thanks in advance.

balticgreen

When you say that the door wouldn't open, do you mean that it was locked and would not unlock or that it was unlocked but pulling on the door handle didn't do anything? Also, when you say you tried from inside, are you referring to the inside door handle or attempting to unlock the door using the interior lock/unlock button?

balthus

It's the lock knob we think. Just went outside and door opened but you can see that the lock knob is not extended all the way up like the others in unlock position. My husband wanted to try using a pliers to pull it up but I was worried it might mess something up. We closed the door & of course now it will not open again.

balthus

Pulling on door handle when car is unlocked doesn't do anything except it seems about once every 24 hours. Thanks.

balticgreen

I'm not a mechanic but it sounds like a faulty lock actuator. Does pulling the lock pin up the rest of the way (you shouldn't need pliers to do it) allow the door to be opened?

balthus

I can't pull the lock up manually. Thats why my husband was going to try using pliers. I just am surprised this would happen with only 23000 miles on the car but of course a month after warranty expired!

eboueiri

That's amazing it failed so early. I know this is a little too late now but I would think the Mercedes rep for the Dealer you go to to should've taken care of it at the time.
It happened on my 2010 GLK350 too and same door as yours but around like 60K miles and it went away. then it became permanent around 110K mikes. I also agree with balticgreen and believe it is the door module.
At first I thought the lock knob was dirty and jamming making it hard for actuator to lift it (dust build up over the years). So I sprayed it with WG40 and massaged it by hand by lifting it and locking it manually few times. It didn't help.
Next time I took a look at it. I took the door panel off and used lithium grease spray. Because some days it worked and other days it didn't. But that still didn't work.
the third times I took a look at it. I checked the module and traced the wires that came from the actuator (I believe it was the green and white wires). I used a 12V power supplier to check if it was the module or the actuator is the issue. I disconnect the terminals and directly contacted them to the 12V power source and Bam it worked like a charm. I reversed the wires between positive and negative and it locked. I did that couple times and I became convinced it was the module not sending enough voltage (current). when I connected it back to the module, it started working just fine. I was like cool. That was easy fix. RIGHT!!
Lasted about a week or two then back to being stuck. I orders a new module from ebay and replaced it but then again it didn't solve the problem.
So I Thought I had it figured out but then found myself at ground zero again. Changing the actuator is a pain from what I saw on youtube and not being 100% sure it is the issue doesn't encourage me down that path.
I am thinking it could be a wiring issue (high resistance due to using a smaller gauge or a splice in the wiring cable or it could be terminal crimp issue because when I used a car battery directly to the actuator and bypassed the module, it worked like a charm.