[W126 Coupe] Rear Driver Side Window Works

[Dick Spellman]

Hi Ernie,

I asked about the opposing rear window because if it works the fuse is
good.  Opposing windows are paired and fused.  So, you should inspect the
rocker switch next.  On the early year SEC's (82-85 or so) the left and
right side switches are one complete assembly.  So, I would remove the
ashtray (2 screws under ashtray insert) pull out tray assembly, disconnect
the electrical lead to lighter, coin cup, shift bezel, and slide the console
wood forward then lift carefully to access the wiring harnesses under the
switches.  By lifting up the wood you should be able to visually confirm all
the harnesses are plugged in on the bad window rocker switch.  If it's not
connected there's your problem. Just reconnect and you are done.

If it is connected, but you still have no window operation,  I would pull
out the electrical schematic on the MB Service CD and using a volt meter
test for the  presence of 12VDC at the socket with ignition on.  If no
voltage is present you have a break somewhere in the harness. See the next
paragraph for one of the likely failure points.  If voltage is present. I'd
go ahead with a tear down of the switch.  Start by removing the switch from
the wood console trim (it just pops up from the bottom and out the face of
the wood trim).  On a clean bench carefully remove the hinged rocker switch
cover (using a fine right angle pick separate the hinge from post to either
side).  There will be a post, spring and ball contact stem under the switch
cover.  Tear the switch down and clean this up with q-tips and iso-alcohol,
dry it, then add a bit of grease and reassemble.  Check the switch for
smooth operation then plug it back into the harness and test the window
again.  If it works great.

If required, visually inspect the door hinge area where the rubber boots
(early models have 2 rubber tubes vs the later year single rectangular form)
and electrical harnesses and door lock vacuum line run from the cabin to the
door.  Are they cracked or missing or do you see any signs of wires that are
exposed and damaged?   If the boots are okay and no wires frayed/exposed at
this hinge point, you need to remove the door panel.  If you do see damaged
wiring at the hinge, it needs to be soldered in a western union splice with
slack added if needed and the boots replaced.  Ask me how to do the boots
with wires and vacuum lines in place only if this is the problem.

As for the door panel removal, it will be presumed that the motor has failed
or you have a stripped motor gear or missing worn regulator teeth.  I have
had one bad motor, numerous lift failures (the $3 nylon glides) and one lift
cracked from metal fatigue on the 6 or so 126 chassis cars I've owned.

The door panel removal goes something like this on the passenger side.
Remove the chrome end cap on the door upper edge near the strike (3 small
Phillips screws)
Remove the chrome trim at the hinge area upper edge (2 small Phillips
screws)
Remove the strike (door catch) chrome trim (2 small Phillips screws)
Remove the flat black plastic trim on the side view mirror (this pries away
and is snapped in place)
Remove the door seat control knobs (just 2 on the early year 126) (these
pull away) or if you find one difficult, use a fine right angled pick set up
under the knob to help pull it away
Remove the really small cir-clip on the post behind the seat back knob if
it's there
Lift the black flexible plastic trim cover behind the interior chrome door
handle.  I use a single blade razor (to avoid cosmetic damage) at the front
and center (top to bottom) of this piece to lift this by prying the 2
plastic tabs clear of the metal cage that it sits in)
Now you should be able to see, access and remove the small Phillips screw
that secures the metal cage affair behind the chrome door handle
Next locate and remove the large Phillips bolt at the top of the long vinyl
clad door handle that is located in the cage area behind the chrome door
handle hinge (this may be covered with foam-just push it aside)  It's tucked
behind the chrome door handle hinge point so pull as to open the door from
inside and you should be able to locate it and loosen completely
Now the 2-piece horizontal) bezel surround on the door wood trim needs to be
removed.  The front cage is snapped into the seat button control box with 2
metal tabs you need to lift away the bezel and separate then remove the
bezel from the switch box.  Be careful not to stress the wood trim which
remains in place
This is not difficult but, the door handle will need to be lifted so you can
clear it while removing the front cage and bezel
Next locate and remove the second large Phillips screw in the base of the
vinyl door handle (down near the door pocket)
Remove the courtesy lamp holder from underneath the door and tape off each
lead if the plastic insulator is broken or missing on one(hot).  There is
voltage present when the door is open so you don't want to short the leads.
Press the two electrical leads into the door cavity.  They will need to be
pulled from the back of the door panel in the next step.
Remove the vinyl door handle
Depress the door lock stem.
Now carefully lift the entire door panel straight upward to clear the upper
rail tabs on the interior window brush and the tabs that lock the panel in
place around its perimeter (it's okay to lift the rear of the panel and then
the front to free the clips up all the way around before final panel
removal.
You do not want to break any of the tabs that ride in the window brush along
the top of the door panel so getting these clear before pulling the door
panel away is critical
You will need to clear the straight door lock stem (only on early year 126
MB's).  Later models have the knob that must be unscrewed.
Once the door panel is free reach down and pull the courtesy lamp leads from
the rear of the panel.

The above should give you a successful door panel removal on the early model
sec.  Please refer to the manual for images and to affirm the steps if you
have it available.  I wrote this from memory on the sec 2000/2002 time
period when I gutted this car and restored.

Now with door panel removed, you should see the plastic film dust cover
which can be carefully lifted and taped out of the way for now so you can
see inside the door cavity where the motor and regulator reside.

Let me know when you get this done and/or post the list so the steps
for *securing
the window glass* and subsequent regulator with motor attached removal can
be detailed.

The motor and regulator can be visually inspected and tested with 12VDC on a
bench.

Regards,
Dick



On Fri, Jul 8, 2011 at 8:19 PM, Ernie <ernietsg at gmail.com> wrote:


> Hi Dick,

>

> I don't know if this is redundant but I responded to the MB email number

> that was assigned to your reply (I don't understand the MB mail protocol).

>  To answer your question,  all the windows except the passenger door window

>  work; do you have any other suggestions?

> Thanks,

> Ernie

> ernietsg at gmail.com

>

>

>

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