My rear driver's side door won't lock/unlock with the rest when central locking is activated. It has to be manually locked/unlocked. I have a '99 E320. Does anyone know what could be wrong and how I can fix it?

 

WAG....

examine for broken/leaked vacuum line from the PSE pump beneath the rear
seat. pull the door panel, cycle the locks and determine if air is getting to
at end of the line

 

Yep, that's it. I have a broken (cut in half) vacuum line. Wouldn't you know it's just inside that black rubber protective cover.

There's very little slack in the line, so I can't pull it out any further. Would it be easier to try and repair the connection (splice in a connector?) or run a whole new line through (and just how would I do that?)?

 

refresh my brain. where is this black doo-hicky? is it a fitting that the hose enters? also, where is the location...within the door?

 

The black doo-hicky thing covers the lines coming out of the car frame into the door. It's located between the door and the frame. It's like a black rubber tube (looks like an accordian). It's easily removable and inside it is where my line is cut.

 

proper way: rethread and replace the hose. i am guessing (have never had to
do this) it'll take several hours of labor and few dollars for the hose. but if you
buy an MB replacement hose, it'll be $50...you get the idea.

backyard mechanic: i wonder if you can get to Home Depot or Lowes Hardware
or some such and find an inline hose splice fitting. you'll need to determine the
ID measure of the hose. eyeballing it, it's in the neighborhood of 3/32, i dunno.
but perhaps you can buy varying sizes and return unused ones.

this is the kind of fitting I'm thinking of



the dealer may have some but you'd have to identify them. e.g. say it's for PSE hose
splicing.

i've used similar for motorcycle and car modifications, such as air horns. what
do you think (or anyone else out there)? too ghetto?

 

I think to gain access to it, follow the same procedure for removing the interior door panel as noted in the DIY for window regulator replacement.

Do you agree Raymond?

 

one would think so, MB. i had presumed that OP pulled off the door panel to
diagnose. whether he did or not, to replace the whole hose, he will still need
to pull the carpet and access behind the lower B pillar. this job is 99% labor.
the part is pennies...a simple hose.

i've not had to replace the hose to any of the locks so can only theorize. I
took this photo when guy installed my multi-contour seats. the hoses were
drawn from the PSE to the front seat bladder controls.

 

Thanks raymond g-.

What I did (ghetto or not) was purchased a piece of vacuum hose from my local auto parts store and re-attached the PSE tubes together that way. They didn't have a small enough inline hose splice fitting and I thought that might restrict air flow too much. I just cut a small piece of rigid vacuum hose and inserted the PSE tubes inside of it. I'll use some clear caulk to seal it. IT WORKS GREAT NOW. I can't believe I fixed it myself. Thanks raymond g- and other forum posters!

 

you get the ghetto, redneck , aka "Bubba Award" award of the week.
seriously, that's a good McGyver fix. of course your logic is sound in respect
to the ID and possible air restriction which I didn't take into consideration.
good job.