How to Refurbish Mercedes Switches

[83mercedes]

Hi all,

As you may or may not know, the switches in Mercedes vehicles can be troublesome after so many years, and replacements are not cheap. However, rather than buy new switches, I have created a detailed, step-by-step process to refurbish the switches at no cost and hopefully get your electronic accessories working again. The switches tend to get buildups inside which reduce the functionality of their mechanisms and sometimes make them stop working or only work after many tries. The following procedure shows how to remedy these problems after disassembling these fairly simple units, and gets your switches working like new. It applies to almost all switches used in Mercedes W123 and W126 chassis vehicles, and possibly other chassis vehicles as well.

TOOLS REQUIRED: Clean work area, very small, thin-blade, flathead screwdriver (eyeglasses one would be good, or small electrical type), dental-type pick(s), appropriate grease (I used lithium), and a telescoping magnetic wand (not necessary, but helpful). (See picture 1)

For ease of communication, I have constructed nomenclature diagrams with all parts in question labeled. (See picture 2)

1. Remove the switch from its console. Whether the switch is in your shifter area, the wood up in the dash, or around your AC controls, the principal of removal is the same. The panel must be removed, either partially or completely, to allow you access to the underside of the switch. This varies for each panel and model, so I will not go into each procedure.
Once you have gained access to the bottom of the switch, reach up or look up under the switch. You will see or feel the two securing metal prongs, one on the forward and one on the rearward side of the switch (picture 3). Depress both prongs simultaneously and push up the switch from below. The switch should pop up and out easily. Now unplug the electrical connection and leave the connection hanging in the appropriate spot so you don’t forget which plug it goes to (picture 4). You now have the assembled switch body in hand.

2. Pop out the switch faces/plastic rockers. Slide the flat head of the small, thin screwdriver between the switch body and the plastic rocker to the side of the mounting hole in the switch body (picture 5).

[83mercedes]

Gently pry out and up. Holding upright, gently repeat on the other side (picture 6). It should have easily popped out. Be careful not to the spill any of the internal components. If it is a window switch, repeat the procedure for the other rocker. Set the plastic rocker(s) aside.

3. Tap out the ball bearings and electrical actuators/metal swivels. SOMEWHERE WHERE THERE IS NO RISK OF LOSING THE BEARINGS (don’t ask how I know), upturn the switch and tap it gently on a hard surface until the two bearings and metal swivels fall out (picture 7). The swivels are the brass-colored, v-shaped metal actuators that will fall out (picture 8). Set all loose components aside. BE CAREFUL WHERE YOU PUT THEM! It’s not fun crawling around on the floor looking for ball bearings, trust me. If you do lose them, a magnet can be helpful.

4. Clean the internal components and swivel rails of the switch. Now, if your switch is like mine were, there will probably be crap inside the body on your pin connectors, on the metal strips connecting your pin connectors to each other (if the switch has those), on the swivel rails, and just lying around in the body of the switch. I believe this stuff just filters in over the years and gums everything up. Maybe I had a slob for a previous owner. Regardless, get all fouling out, but CAREFULLY. Use your flathead screwdriver to gently scrape the swivel rails clean if they are dirty or grimy (picture 9). Use your pick(s) as a dentist would; to scrape off any offending material from hard to reach places (picture 10).

[83mercedes]

THE NUMBER ONE CULPRIT IS THE TOP OF EACH PIN CONNECTOR INSIDE THE SWITCH. This is the point where the metal swivel hits and makes the switch go on or off, up or down, etc., when you press it (picture 11). IF IT IS GRIMY, IT MAY BE YOUR PROBLEM. Use the pick to carefully scrape the dirt, carbon, whatever it is off until you see clean metal, but not further. Periodically shake the switch upside down to get out all the debris you have dislodged. Once you are satisfied that the inside of the switch and the swivel rails are impeccably clean, move on.

5. Clean the electrical actuators/metal swivels and ball bearings. Typically, after 20 or so years of service, the grease that Mercedes put in the middle of these metal swivels for the ball bearing will gum up, get crusty, and impair the operation of your switch. Use a Q-tip or similar cleaning tool to get all the dirt, grime, and old grease off of the metal swivels. PAY SPECIAL ATTENTION TO THE ENDS OF THE SWIVELS (picture 12). These are what actually come into contact with the pin connectors and transmit the charge. Rub the ball bearings clean. All bare metal should be visible. A de-greaser may be necessary for especially stubborn buildups, although I found scraping with the flat-head screwdriver provided better results. When finished, set all components aside.

6. Grease the electrical actuators/metal swivels. Using your flat-head screwdriver, scoop up a small dab of grease and apply this to the middle of the metal swivel, where it comes together in the bottom of the “v” shape (picture 13). Use the grease sparingly; this is not exactly a high-stress bearing and excess will clot up and make it nasty again.

7. Reassemble the unit. This is where the magnetic wand helps. Using the magnetic wand, lower each metal swivel into the body of the switch until the bottom of the “v” rests in the actuator rotation points (picture 14). Use the flat-head screwdriver the separate it from the magnetic wand and lightly make sure it is in place. If you are without the wand, you could use very small pliers or simply drop it into place (though that gets frustrating). Once the metal swivels are in place, drop each ball bearing into the “v,” where it should be sitting in its little dab of grease. Now that you have that positioned, take your switch face/plastic rocker and lower it evenly down into the switch body so that it rests on top of the ball bearings. Snap it into place. Test the movement of the switch. If something feels funny, remove the plastic rocker and check that everything is in place. Lower it back in carefully and straight down so that it engages the ball bearings.

8. Install the switch in vehicle. Orient the assembled switch into its original position and reattach the vehicle plugs to the pin connectors on the bottom of the switch. Slide the switch down into its spot. You do not need to depress the prongs.

Now your switch(es) should work like new! I’ve had great success with this procedure, and I hope you do too (mine were nasty, see picture 15). Best of luck!

[whunter]

I just sent a request for "Bill" to add this DIY to the wiki page.

Great job.

[Mismost]

Great write up, thanks for taking the time to share with all of us!

This what my Dad calls the C&C factor....crap and corrosion...it kills all kinds of things.

[Jeremy5848]

Good job, thanks.

[83mercedes]

Thanks all. I'm just glad I could be of help. I hope everyone has as good luck with this as I did.

[Phil]

I found that after you get the switch all apart it helps to flush the body out with electrical contact cleaner, it removes a lot of little crud. The best thing I found for cleaning the contact faces is a pencil eraser and when you put it back together use a small dab of dielectric grease to hold things in place during reassembly.
My two cents.

[Bill Wood]

Originally Posted by whunter

I just sent a request for "Bill" to add this DIY to the wiki page.

Great job.

Thanks for the DIY!
It's in the Wiki HERE.

[Captgrail]

FYI, These instruction works for a 107 window switch too. Only difference is the switch is half as big. (2 seater!)
I echo that instruction when you take it apart do it very carefully with a very thin tool, not a fat flat edge - I used a metal nail file. My car is an 84 and the plastic is very brittle. Another point is to try and disassemble it from the top to reveal where all the internal parts are positioned THEN dump them out on your worksurface - like a paper towel. You won't have to worry about loosing the little balls either. It took me longer to take the dash apart than to clean the switches. Once back in place, make sure you seat the switch all the way into the electrical socket. Thanks for the article, simple easy fix!

[Grnburg]

I figured this out for my '84 300 wagon and got my right front and rear windows working again... for about 4 weeks. They gradually took more and more tries to get the windows back up. The day the front drivers window didn't budge after 3-4 minutes of praying and button pushing I had to do it all over again in the parking lot at the correctional facility where I work. They don't let us leave our cars open when unattended! I just did it again after about 6-7 weeks - at work again; why do today what you can put off for tomorrow? Each time the same posts were crudded up.
The problem seems to be that the contact posts inside the switch are worn down from 23 years of use and get a build up of corrosion eventually blocking current. Electrolitic grease didn't stop this. I'm considering building up the posts w/ solder, theory being that the slight gap is causing sparking which creates carbon residue thus blocking the current when too thick.

[pcsreasier]

Originally Posted by 83mercedes

It applies to almost all switches used in Mercedes W123 and W126 chassis vehicles, and possibly other chassis vehicles as well.

Of course, I have a W124 and I can't get beyond the "1. Remove the switch from its console." part. LOL. It would be a little bit easier if I was more mechanically inclined I imagine.

This DIY is superb with great instructions. I was excited thinking about and at least trying to repair the switch, if not replacing it. But I'm stuck coming out of the starting gate.

I can't seem to find (let alone get to) the metal prongs. Is it possible that the switches are anchored differently for the W124?

[hangit]

Do the W123 rocker switches have light bulbs?

John

[pcsreasier]

Originally Posted by pcsreasier

Is it possible that the switches are anchored differently for the W124?

Well.....I can answer that one myself now. I just got a grip on the switch and pulled (living dangerously) and out it popped. There were no clips that I could see. So, I put one of the rear window switches in for the driver's and don't use the rear window until I repair the switch or get a replacement. So simple.

[dufflespank]

Yeah, does anyone know how to get the switches out of the center console in the w124? Do you just pull on them?