Window switches problem
 

So, all of a sudden my passenger window won't go down. I recently replaced the console trim, so I feel like it must somehow be related to that - that particular switch was making poor contact, so I had to press down a little bit on the wood trim, which worked intermittently, but now is no help at all.

I've swapped the driver's-side and passenger-side switches - both work in the driver's-side position, so it's not the switch. When I depress the switch, I do hear sort of a click, like a relay going off, but no movement. Could it be a motor or regulator problem? It just seems way too coincidental for something in the door to fail right after I was messing with the switches.

Thoughts?

Another thing, does anyone know how to release the bottom halves of the switchgear from the black plastic panel underneath the wood trim, like in this picture: http://cdn4.pelicanparts.com/techarticles/Mercedes-W124/131-INTERIOR-Window_Switch_Replacement/images_small/pic04.jpg

I didn't think it was possible, until I saw that picture, but I can't seem to remove the lower halves. But, I'm also trying not to force it too much and break anything.

They just unplug, but there is probably a bit of corrosion if they haven't been unplugged in the past 25 years.

A little spritz of electric contact cleaner on the wires on the back of the plugs will make it easier to unplug the connectors from the switches.

Grasp the top and bottom of the switch (on the unfinished side of the console panel) with one hand.
Then grasp the top and bottom of the plug with your other hand and gently rock the plug top to bottom while tugging at it.
It may be a little stiff at first, but they do eventually unplug.

On the DS window switches, I find it is easiest to first remove the central child lockout plug by rocking it side to side, before unplugging the DS front and DS rear window switches.

Maybe I'm not understanding you - I know how to separate the upper male half of the switch from the lower female half. I'm asking if the lower female halves comes loose from the plastic panel that they all look snapped into. Is that what you're talking about, too?

Ah, I think I misunderstood your original question.

I believe you want to know how to remove the switches from the wood panel without damaging the panel.

1) From underneath, squeeze one (either top or bottom) of the integral metal spring steel clips flat with your finger or a blunt key.
You may have plastic prongs rather than spring metal clips on your switches
Avoid using a screwdriver as you may shear off the locking tab in the wood panel if the tool slips.

2) Simultaneously, gently push the same (top or bottom) pin side of the switch up to release the switch fom the locking tab of the wood panel.

Repeat step 1) and 2) on the other side of the switch.

Once the top and bottom of the switch are released from the locking tabs you can push the switch up and out of the wood panel.

No, I'm sorry, that's not what I mean.

Okay, picture this: you remove the wood panel, and the upper half of the switches are clipped into the trim piece. You look underneath, and the lower half of the switches are clipped into a plastic housing like this:


Anyway to get the lower switch halves out of this plastic housing, without breaking anything?

Also, does anyone have any ideas about the sudden loss of window function?

Thanks.

It's about the same process as described above (that was for a 123), on a 124 the switches are clipped into the plastic frame, and release from below in a similar manner. There are release tabs that need to be pushed in and then the switch pops out of the frame.

Your 1992 W124 has the convenience control system with the express down feature. Unlike all prior models, where the switches in the console directly switch the motor current, the switches in the console just send low current voltage signals to the convenience control module located under the left rear passenger seat. This module actually does all the switching of the four window motors.

If you look at the long ends of the switch where they push through the plastic crib, you'll see a tab on both ends, one will be longer than the other. Use something skinny but sturdy like a paring knife and pry gently on the long end (usually towards the top of the panel) while also pressing on the switch. It'll just lever out.

Did you have the switches out to swap driver/passenger in your test above? Can you elaborate on what you did and what the results were?

Got it!, I 'm familiar with the W116, W123 and W126 consoles...I hadn't seen that style before.
The photo really helped!

From the photo it looks like you need to wedge a small screwdriver or plastic bone tool between the side of the plug-in connector and the outer "ear" on the plug holder.
This should allow you to free the plug-in connector from the plug holder.

As to why the the PS window function failed...possibly frayed wiring near flexure point in PS door, bent regulator, siezed window motor, loose/corroded pin receptacle (female side) of console PS window switch connector.

I'm leaning toward the last option, as you had intermittent operation of the PS window when you pressed harder on the PS switch.
You should be able to open the plastic body of the plug-in connector and remove the wires (take a photo of wire locations beforehand to aid in reassembly).
Lightly, gently crimp each female connector so it will have better contact with the male pin when the connection is renewed.

Hope this solves your loss of PS window function.

Thanks all for the info. Oddly enough, about halfway through my commute this morning I decided to try the window again. The first time I got the relay clicking noise, and then all of a sudden it worked. Auto down, up, repeated several times, worked every time.




So the release tabs are on the tops side, and then push up from the bottom? Or vice versa?



That explains why I heard the relay clicking back there. Sounded like it was coming from the same place as the heated seat relay, which was clicking until I had everything hooked up and fused properly.


Yes, I switched switches L to R, and the R side continued to be inop. Bothe switches worked on the L side.


Thanks! If I can free the switches from the plastic frame I'll definitely have a look at the pins...at least clean them up. I've already taken apart several of this style of pin connector on various places throughout the car.

Ok, so how's this for weird? I get back in the car to drive home and the passenger side window is no longer working (again). Just relay clicking noise. About 2-3 miles into the drive, I tray again - and it works! WTH? I've never heard of a switch having to "warm up" before. Make me think it really must be something to do with the contacts. Will dig in when I get some time.

I'd suspect contact problems as well. Either in the plug or somewhere in the wiring. Driving the vehicle causes vibrations that can make an "iffy" connection work again. Could also be questionable solder joints in your "convenience module" wherever it may be.

most likely. backseat left side. remove the bench you'll see it. on the other side is a vacuum pump for the door locks etc

Windows have all worked for the last week and a half, and then all of a sudden the passenger window stopped working again. The switch is plugged in all the way, so I don't think the issue is there, even though I was messing with the switch right before the first time this happened. Now that I think about it, I also pretty recently messed with the convenience module - I had to move it in order to install the heated seat relay, which fits underneath.

I read somewhere to test the convenience relay by holding the key in the locked position, and that all open windows/sunroof should close (I didn't even know I had this feature!). So I tried it - driver's side goes up, nothing happens with the passenger side. Supposedly this is a completely different circuit than the switch, so it eliminates the switch as the problem (I guess). Obviously the relay isn't toast, because some of the windows work - are there individual solder joints to each window? Are they repairable with a solder gun (I assume yes)?

Time to check motor connections I think.

Does the fact that the convenience relay "clicks" when the switch is depressed mean anything? I mean, obviously the signal is making it from the switch, right? I'll pull the relay this weekend but I'm not sure if there'll be anything visibly wrong with the thing.

I'd start at the window motor. Hit the connector with a multimeter and operate the switch. If you get 12V you know the switch and convenience module are good and the problem lies in the motor or window regulator mechanism. If you don't get 12V, you know the problem is in the convenience module or the wiring between it and the motor (always possible you could have a broken wire in the door!).

So I started by checking fuses and cleaning all of the contacts on the convenience module, because that was a lot easier than the prospect of pulling the door card - but of course, no luck with that.

Anyway, I moved on to the door card and finally got it off. Sorry for the crappy pic, but are these the contacts for the window motor? I'm pulling about 12.25 volts with the window switch pressed up or down. The motor isn't running, so I assume the problem is not the regulator. I guess I'll try to whack the motor with a hammer or something (it's a very tight fit, though) and maybe I can get one more push out of it - but otherwise is there any way to raise the regulator manually so that I can drive around with the window closed while I source a new motor?

If everything is working correctly, you should get ~12V in one direction and -12V in the other. For example, if you have your red lead on the left screw and black on the right, if you press "up" and measure 12.25V, you should read -12.25V with the leads in the same spots but pressing "down".

If you're getting voltage all the way to that point, you probably have a dead or dying window motor. They can seize up, the plastic gears can break, or the brushes can get jammed in the holders. If you pull the window regulator and remove the motor, most of them come apart and you can probably get it working again with minimal effort.

Of course, nothing is as easy as it's supposed to be. This window regulator is a serious PITA to remove, and is made more difficult by the fact that I don't want to break what might be a salvageable regulator, and I really don't want to break a window.

The only regulator I've ever worked on was a BMW 318ti - similar in theory, but access was way better once you got the door card off. But I digress...

Anyway, you can see in the picture below that I have two problems:

1. The stupid brass-colored speaker frame is in the way, and it's riveted in place. One of the online DIYs suggests drilling out the rivets, which is great, but it seems like the thing would be destroyed afterwards. How would I go about reattaching this frame so that I can remount the door speaker?
   
2. The damn plastic slider is just short of slipping through that slot on it's left, which would release the window. The window is angle as much as it can go, and it's still not enough...I don't get it. Something else that confuses me is that the DIY I'm looking at, as well as the FSM, show that particular slider to the left of the little exit slot. WTH. Should I start unbolting the regulator from the door frame and see if that helps maneuver it a bit more? Also, I had an extra white plastic slider to the right of the one shown - it wasn't attached to anything, it was just hanging out. Surely it's meant to be attached to another arm somewhere - is this the root of my problem?

(BTW, yes - I was getting corresponding + and - voltage values pressing up and down on the switch)

Drilling out the rivets is more elementary than you think. Use a drill bit roughly the size of the head and drill until the head comes off. The rest of the rivet will push out the other side. You can reattach with new pop rivets, or nuts and bolts.

I haven't worked on a W124, but if it has anything in common with the W126, unbolt the regulator mechanism, and you should be able to move it around enough to get the sliding jaw out of the slide track.

Again, being unfamiliar with the W124, the W126 has a 2nd sliding jaw in the front windows that meshes with a track in the vertical direction. The idea being that it keeps the window from rattling when partially rolled down.

You might try giving the motor several hard whacks with the handle end of a screwdriver and see if you can get it to behave long enough to maneuver it up or down so you can get better access.

Is the glass still mounted to the regulator frame? Sure looks like it in the pic, if so they. Should be separated.

The forward arm is unbolted from the rail. Isn't the rail integral to the window?

Not certain where you are stuck but maybe this will help.

http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD2/Program/Chassis/72-185.pdf

Now I'm thoroughly confused. On the bench, the motor works and drives the regulator in both directions. I theorized that perhaps the extra work of lifting the window was enough to make the operation kaput. So then I connected the contacts in the door back to the (uninstalled) motor and regulator, and nothing. I don't get it - according to my multimeter, I'm getting 12+V to these contacts when the switch is depressed. What gives?

EDIT: Okay, never mind. I don't think I was completing the circuit. The motor now operates when hooked up to the door. So my question now is, why doesn't it work when installed - could it be the weight of the window, as I theorized before? Or did messing with the assembly just get it working again (temporarily)? I will probably reinstall and test, and see if I can at least get the window closed, but I'm wondering if I need to be shopping for a new motor or what in the meantime...

Try attaching a 12V light bulb to the contacts in the door and see if it lights. That will prove out the wiring.

See edited post above - got it working (but not in situ, yet).

I suspect you have a poor connection in a wire to the motor or brushes that are intermittently making/breaking connection.

Get the window motor working and wiggle the wires. If the motor cuts in and out, you know you have wiring breaking down. Open and close the door too, you could have faults in the wiring going through the hinge area.

If wiggling and fiddling doesn't produce intermittent results, take the motor apart and make sure the brushes are free to move in their holders and the commutator on the motor is in good shape. You have the style of motor that comes apart so you can check those things. You can also inspect the condition of the worm gear on the motor and the plastic driven gear in the regulator gearbox.

Thanks for all the advice so far! And for bearing with my stupid questions.

I think the motor just might be toast. After being unable to get the motor to cut out while bench testing, I decided to reinstall everything. Got the window all the way up, and then tried down - it only went down a quarter way or so before getting stuck. It went back up, and back down and got stuck on the same place. I thought maybe the regulator was binding up somehow, but I couldn't figure out where. After the third try or so, I couldn't get the thing to budge in either direction - it was just as it had been before.

I got everything back on the bench, pulled the motor off the regulator, supplied power, and nothing. I cleaned some contacts, took the motor apart and peeked inside - didn't really know what I was looking at, so I put it back together. Hooked it back up to power, and it works for a couple of seconds, then all of a sudden the gear stops turning nd the motor starts buzzing - like it's still trying to turn the gear from the inside but is working against resistance. Gently nudging the gear will get it to spin a few more revolutions and then get stuck again.

So now I don't know if the motor is just progressively failing, or if I just screwed it up worse by taking it apart (I don't see what I could've done to it).

Anyway, if I knew more about this kind of stuff I might be able to fix this, but I'm not sure. I may just end up needing to shop for a new motor, and possibly just replace the regulator while I'm there. At least with new parts I'll know it should hold up a while - but the price for OE parts is insane, and aftermarket quality is suspect. For things like this I usually like to split the difference and go OEM, but it looks like the Bosch motor might be NLA. I guess eBay is another cheap option, but I'm not sure how much of an improvement another 25-year-old motor would be, lol.

How easy is the motor shaft to turn? It should be relatively easy. If it seems stiff or it takes effort to turn it, the bearings may be in need of lubrication.

If you take the motor apart, there is a copper ring with a bunch of segments in it that makes up the commutator. On it ride 2 carbon brushes (chunks of carbon).

Take some Q-tips and soak them in acetone and clean up the surface of the copper commutator and the faces of the carbon brushes where they ride on the commutator. Make sure the brushes can freely move in and out of their holders. If they can't, pull them out and clean them with the Q-tips as well.

Before reassembling, clean out the bronze bearing in the end plate with a Q-tip soaked with acetone. It'll be pretty mucky. Clean off the motor shaft where it passes through the bearing as well. Lubricate it with something like Zoom spout oil or 3-in-1 oil in the blue can (will say for electric motors). Make sure to lubricate the felt wick on the motor-side of the bearing as well.

Reassemble the motor and try it again. If the brushes have good contact with the commutator and you got the lubrication done to the motor, it should run fine. There's just not much to it. What tends to burn them out is when the bearings bind up and seize or the windows jam in their tracks and people continue to try to operate them.

FWIW 3 of the 4 motors in my SDL had the same issue you're facing. The 4th was an aftermarket motor and was completely dead. The 3 motors I repaired are still working fine today and are original to the car.

Using the correct oil for lubrication matters too. Don't even attempt to use grease for the bearings. It'll work now, but it won't for long. If you use engine oil, it will attack the brass in the bearings and cause it to wear very quickly. Using a detergent-free oil such as Zoom Spout Oil or 3-in-1 in the blue can will keep it humming along for another 25+ years.

I guess I'm just not seeing all that stuff that you're talking about. There are two Torx bolts that, once removed, allow the two halves to come apart - one "male" end with the worm gear protruding, and then the other "female" half which accepts the worm gear in order to drive the 10-tooth gear. I imagine the male half can be further disassembled, but I couldn't see a way that didn't involve braking the housing somehow.

There are a couple of screws on the motor itself that allow it to come out of the housing. It's been >18 months since I've had mine apart, so I don't remember the specifics. The whole worm gear part will pull out of the motor "can". You'll see the important parts inside.

Hmmmm. There are a couple of Torx screws as I mentioned, but the housing itself looks sealed. I don't see any other fasteners anywhere else other than rivets.

I decided just to spring for a new motor, because I want to get this done ASAP and move on to bigger projects. The OE part is anywhere from $300-$400, which is crazy. THE OEM Bosch part was discontinued in 2013 and is NLA. eBay is full of salvaged parts that are cheap, to be sure, but could fail tomorrow for all anyone knows. I finally settled on a reman from AutoZone because it should be delivered to my front door by the end of the week, and it was only about $100 with free shipping, a 10% off coupon, and the core charge refund. Maybe it won't last another 25 years, but I suspect I'll have bigger problems before then anyway, lol.

BONUS ROUND! There are a few things I still don't get. One is this extra slider, item #1 in the picture below. It was just sitting there, in the window rail, not attached to anything. It's shown in the EPC diagram - but again, not attached to anything - which is odd - surely it serves some function? #2 is a body-colored vertical rail. Is that just structural reinforcement, or is there supposed to be a slider in there? FOr example, item #3. Clearly some sort of slider, same plastic as the others and greased up the same as well. I found it loose in the bottom of the door. That can't be good, right? lol

http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD2/Program/Chassis/72-185.pdf

There are normally three sliders.

The "extra slider" is the front "slide shoe" that attaches to the front lower regulator arm (Fig. 172-29717 by step 6).
It may have been left behind from a prior repair of the regulator arm, and that's probably why you have an extra.
The metal pin that attaches it to the regulator arm is missing.


The rear slide shoe attaches to the rear lower regulator arm (right side of Fig 172-29710 by step 7).


The front and rear slide shoes are attached to your regulator arms, so you can safely remove and discard the "extra slider".


The "mystery slider" is partly visible in the left side of Fig. 172-29710 by step 7.

It ties the rear vertical guide rail to the horizontal guide rail.
It should be re-installed.

The three sliders are also visible in the photo on Post 5 of this thread:
sticky or DIY for front window regulator replacement? - Mercedes-Benz Forum

Hope this helps.:)

That's kind of disappointing about the motor not coming apart. I suspect Bosch changed the design slightly between 1986 and the mid 90s, so that's kind of a bummer.

That curved sliding piece does go in that body colored channel. When I looked up info for my SDL it gave the part number in the EPC for it, but gave no mention where it was installed. Both of mine were down in the bottom of the door, so it took some trial and error to figure out just where they went. It serves 2 purposes - it helps to guide the window and it helps to keep it from rattling or jumping the track when partway rolled down and the door is slammed.

If you have slides that are missing or broken, the extra strain on the motor could be what's been causing you grief.

Gosh, I feel so dumb! Parts #1 and #2 in the pic above (AKA extra slider and mystery slider) are in fact THE SAME PART, which serves to connect the regulator to the body-colored rail (#3). It broke in half! Which explains why half of it was still captive in the regulator, and the other half, which rides the rail, fell down to the bottom of the door. And also probably explains the extra stress on (and eventual failure of) the motor, as Diseasal300 mentioned. Well, another part to order. Nice to put that one to bed, lol.


On another note, any suggestions on what to lube up the new motor and sliders with? I've got a little bit of Gleitpaste, some white lithium grease, some graphite powder...and an O'Reilly's in town.

Mystery solved. LOL!

I used silicone sunroof grease to lube the tracks in the SDL. Seems to be what Mr. Bergsma recommends as well. I chose it since it won't harden or react with water, so it won't become "gummy" as it ages.

Well, everything was going great, until this happened:


Still not sure what went wrong, exactly. Got everything back together and tried raising and lowering the window. I was getting some resistance and binding, and kept disassembling and reassembling - the main issue was how exactly to fit that "sliding jaw" (the so-called "mystery slider" from a couple posts prior). No matter where I put it, it seemed to interfere. I finally just removed it entirely to check if there were any other points where the window was binding. I started to raise the window, everything looked good, and all of a sudden without any warning at all - BOOM! - the glass shattered into a million pieces.

Now that there's no glass there, the regulator moves up and down without any problems, lol. So I know the regulator is more or less assembled correctly. But I still have two problems:

1. I still don't know exactly how to install the sliding jaw
2. Broken glass!

Anyone have any insight into problem #1? For problem #2, I found an OE used window for $39. Pretty good deal, but I'm afraid of repeating the experience if I don't get to the bottom of why the glass broke in the first place...

Now, if you'll excuse me, I've got a huge mess to clean up! lol

Also, is this where the sliding jaw goes? (Obviously the window rail is not pictured)


It's the only arrangement I can figure out that makes any sense, except that it's impossibly tight, no matter how much you lube up the slider and track. It's going to burn out the window motor in no time if I run it this way.

The sliding jaw you show does appear to be in the right spot, although it appears to be a different design than the original one you show further up the page. Are you sure it's the correct part? It should be a snug fit, but not tight.

Before putting in the new window, it would be a good idea to find out what bound up and broke the one you have. I'd suspect it jumped a track!

When they do break, it's pretty alarming. I had a rock come in through my front passenger window in a construction zone once. I thought I'd been shot! Talk about a loud noise! BOOOOOOM!!!!!!!! Had that car for another 4 years and was still finding little shiny diamonds in places when I traded it in...

Thanks for the input. I'll double-check the part number - maybe I somehow got a sliding jaw for another chassis?

All the plastic sliders are still in the appropriate tracks. The sliding jaw was not in place, and the window was about 3/4 of the way closed when it broke. I'm thinking it was not aligned correctly because the sliding jaw was removed - either that, or one or more of the regulator arms are bent or something. I haven't removed the regulator yet to get a good look at it.

Yeah, it was momentary alarm followed by immediate regret, lol. I cleaned up most of everything except all the glass that is within the skin of the door. Gonna have to be real meticulous about that so the damn thing doesn't sound like a maraca every time it slams shut.

My whole day was ruined - was going to put my BMW on jack stands and drain the engine oil and transmission overnight, but now I don't have the garage space to do so (don't want to move the Mercedes outside with a broken window because it's been raining off and on). Oh well!

The window should move up and down freely in its tracks, even if the sliding jaw isn't installed. I haven't worked on a 124, but the 126 has tracks in the doors that the window glass rides in. It's very easy to get the front edge out of the track, especially if you've been fiddling with the window. When you try to roll it up, it will bind, if you don't catch it, it doesn't take much to shatter the glass.

I mention the design of the sliding jaw since it looks different than the one you removed. The new one I bought for the SDL looked exactly like the broken one you had. It would make sense that it would be a tight fit if the one you have now is designed for a different chassis.