I have another question about my 1987 300e (i just got it from my dad so i have to deal with the problems he neglected lol) but anyway, the back two windows don't go down. you can push the buttons and nothing happens. The child safety switch is broken and i'm thinking that has something to do with it. if i replace that switch, would that solve the problem? I found one on ebay for a SEL model but i'm not sure if it would work on mine. Thanks for any input.

It might solve the problem or they might be broken individually. EPC can tell you if the E and SEL use the same switch. You might also be able to just wire around the switch.

https://epc.startekinfo.com/epc/welcome.jsp

Thanks i'll give that a try

Try cleaning the buttons? The inside of the buttons get a fair amount of wear and tear and tend to gum up. They simply snap apart (be careful, there are two tiny ball bearings inside). If you look at the contacts, most likely they are covered in black stuff from old age which you can clean off with some Q-tips and rubbing alcohol. Reassemble and put the switches back in to try them. I also think that the front switches must be operational or at least hooked up to allow power to go to the back windows.

__________________
87 300E
202k on the clock

If all the switches are good (and it is a good idea to clean them) and you've power where it's supposed to be, check the wires that come out of the pillar between the front & rear door.
That's where mine popped out of the braided cover and broke.
Cut the wires, slip on some shrink wrap tubing & re-solder back together. If you have the rear door panel off you can re-adjust the wiring harness so it doesn't bunch up and break again.

Thanks for the tips. I tried cleaning the buttons with some electric contact spray, but still no go. The wiring looks good and like i said the two front windows work. The only thing is that the safety button is broken, and i totally removed the switch and they still dont' work. I don't have a new switch yet b/c i'm waiting for it to come in. Perhaps that switch is causing the problem. I hear click noise from the back windows when i press the buttons, but nothing happens. i can't imagine both motors being broken. gota love mercedes and their back windows lol

? You removed the switch and connected the two brown wires?

no i only cleaned the switches and checked the wiring. should i connect the two brown wires on each switch?

Original reference was to safety switch. Yes, if you connect the two brown wires at the safety switch you will have overridden the switch.

If you are hearing the solenoid on the motor click but nothing is happening, chances are your motors are fried. It seems that the problem with these cars (my mechanic knew all about this when I stopped by last week to ask about repairing the window regulator) is that the window regulators on the back windows are garbage. The gear driven regulators at the front are reliable, but the cables in the back can jam up the motor and then fry it, like what happened to mine. I think it is entirely possible that both motors are junk if you are by passing the switches and they still don't work.

If that is the case, it would be my advice to just leave the windows up and forget about it - new regulators + motors are expensive, especially for a car that is as old as 1987.

__________________
87 300E
202k on the clock

Mine would click like that so I took the gear/motor housing apart and found a little plastic tab had fallen off and gotten wedged in the gears. Its similar to one of the tutorials on the antenna motor located on this board. I crazy glued them back in, greased it all up and it works well.

Man, those switches can be a pain if they're the same ones as in my 126. Those two ball bearings can be a to get back in properly. I have had problems with them before. One time one of the copper contacts that is riveted into the throw arms fell out and lodged itself between two terminals. This caused issues, obviously. I was actually able to solder it back on to the throw, but nevertheless the switch despite testing okay with a DMM would still blow a fuse if you attempted to lower the rear window from the center console switch but mysteriously would work fine if you did it from the defective rear switch. Bizarre.

Before I get too anecdotal here, you need to figure out a couple of things. First, are you getting voltage back there? This will help us determine whether we have an electrical, electro-mechanical, or purely mechanical issue. Check your fuses. On my 126 the fronts and rears are fused separately, and if I recall correctly, across sides. For example my front passenger side window is on the same fuse as my rear driver's side. Why they did that is anybody's guess. But check your fuses.

Second, after you have determined that you ARE getting voltage back there and there isn't some other issue, you need to determine if the motor's shot or the mechanism is jammed for some reason or another. On my 126, the slide jaw for the rear window breaks regularly and this is lame to fix, bit cheap. Listen for sounds of the motor struggling. If you hear some evidence of this then the cause is probably mechanical rather than electrical.

I wouldn't be surprised if the windows hadn't been left in the up position so long that they've stuck inside the track and the motors just can't overcome the initial torque of breaking free. Try having someone grab the glass from both sides with the door open and push down as you actuate the window switch. Don't let them overdo it, though. Don't do this 5 minutes before a rain shower either, in case getting it back up is difficult.

Go from there. Determine if it's electrical or not. Then come back for more detailed help from me or one of the many more knowledgeable people than myself.


Good luck.