Author Topic: W108 Electric Rear Window  (Read 1864 times)

K-Jet

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W108 Electric Rear Window
« on: May 04, 2023, 19:28:32 »
Good afternoon!

When I got my 1971 280SE, one of the niggles was that the passenger rear window would not roll down. I traced the problem to the front window switch and replaced it. Now the window goes down. With the down switch on the door and the up switch on the front switch. I have mapped the connector and matched the wires (and swapped a few!) and done all I can think of, but I can't seem to make the switches go in the same direction.

Anybody solved this problem before, or have an idea how to?

Thanks,

K-Jet
Dru
_____
1971 280SE "Beverly"
1990 250D 5-speed "Opa"
1995 E220T Sportline "Sport Kombi"
1980 911SC Targa "Petrol"

ja17

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Re: W108 Electric Rear Window
« Reply #1 on: May 05, 2023, 04:23:46 »
Probably dirty contacts in the switch. They can be opened up and cleaned. (A bit tricky to keep the tiny spring and ball in place during re-assembly.)
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

K-Jet

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Re: W108 Electric Rear Window
« Reply #2 on: May 05, 2023, 14:54:31 »
Dirty contacts would cause the front switch to work backwards from the back switch? Both switches work reliably in both directions, they just work in opposite directions.

Currently the front switch causes the window to go up when I press up and down when I press down. But the switch in the rear door makes the window go down when I push up, and up when I push down.

Or I can swap the motor wires and the door switch is correct and the front switch is backward.

I metered the switches and checked the voltages and several times came to the firm conclusion that if I only swap this wire for that wire in the connector the switches would both work correctly, but all I got out of that was blown fuses.
Dru
_____
1971 280SE "Beverly"
1990 250D 5-speed "Opa"
1995 E220T Sportline "Sport Kombi"
1980 911SC Targa "Petrol"

rwmastel

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Re: W108 Electric Rear Window
« Reply #3 on: May 05, 2023, 15:29:11 »
Before you replaced the front switch, did the rear switch operate the rear window at all?  Did it work properly?
Rodd

Did you search the forum before asking?
2017 C43 AMG
2006 Wrangler Rubicon
1980 450SL
1966 230SL

K-Jet

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Re: W108 Electric Rear Window
« Reply #4 on: May 05, 2023, 15:39:35 »
It did not.
Dru
_____
1971 280SE "Beverly"
1990 250D 5-speed "Opa"
1995 E220T Sportline "Sport Kombi"
1980 911SC Targa "Petrol"

BobH

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Re: W108 Electric Rear Window
« Reply #5 on: May 05, 2023, 16:12:17 »
Hello, these motors are reverse polarity, so the switches reverse the +ve and ground supplies to the motors.  The front master switch and rear switches should work independently of each other

Have you got a wiring schematic, or are you connecting and changing the wiring around blind?  i think you really need to follow the schematic wire for wire, and then surely both switches should work correctly

« Last Edit: May 05, 2023, 16:18:10 by BobH »
February 1965 230SL Automatic
UK delivered RHD
Papyrus white, blue hard top & hub caps
Blue soft top
Blue leather

rwmastel

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Re: W108 Electric Rear Window
« Reply #6 on: May 05, 2023, 17:48:09 »
If no schematic is available, then just replicate what is working for the other rear window.
Rodd

Did you search the forum before asking?
2017 C43 AMG
2006 Wrangler Rubicon
1980 450SL
1966 230SL

BobH

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Re: W108 Electric Rear Window
« Reply #7 on: May 05, 2023, 18:06:13 »
I found this if you don't have one, hopefully the electric windows circuit is the same for your car

https://www.benzworld.org/attachments/15-17-pdf.419480/

Just a thought, if the switches are plain, unmarked, can they not just be turned around, never seen one, so just a thought

Nice little sketch to show how the switch reverses the polarity to the motor

https://www.12voltplanet.co.uk/downloads/12V%20Electric%20Window%20&%20Aerial%20Switch%20wiring%20diagram.pdf
« Last Edit: May 05, 2023, 19:50:41 by BobH »
February 1965 230SL Automatic
UK delivered RHD
Papyrus white, blue hard top & hub caps
Blue soft top
Blue leather

K-Jet

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Re: W108 Electric Rear Window
« Reply #8 on: May 06, 2023, 12:23:09 »
Bob,

Thank you. The wiring diagram is more complete than the one I have, which only goes to 63.

What would happen if I switched pins 1 and 5 is the same thing that happened when I switched the wires on the motor side- both front and rear switches would work the opposite of what they do now (and still opposite one another).

Maybe the hope is in trading pins 7 and 8 on the front switch (marked 62a)?
Dru
_____
1971 280SE "Beverly"
1990 250D 5-speed "Opa"
1995 E220T Sportline "Sport Kombi"
1980 911SC Targa "Petrol"

BobH

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Re: W108 Electric Rear Window
« Reply #9 on: May 06, 2023, 12:48:32 »
I would trace the wiring and make sure it's correct as per the schematic

5 on the rear switch, black/pink to 7 on the front switch
3 on the rear switch, green/black to 8 on the front switch
February 1965 230SL Automatic
UK delivered RHD
Papyrus white, blue hard top & hub caps
Blue soft top
Blue leather

lpeterssen

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Re: W108 Electric Rear Window
« Reply #10 on: May 09, 2023, 10:47:01 »
Dear Dru

Do you have a digital copy of the oily wiring diagram you show on the picture?

I would like to have one if possible.

I have not replied to your question coming in, but I think that Bob help you right with the correct schematic for later version power windows.

Next time write me per email, I am willing to help if I have the information.

That schematic Bob gave you I have it too.

Best regards
Lp
Bob,

Thank you. The wiring diagram is more complete than the one I have, which only goes to 63.

What would happen if I switched pins 1 and 5 is the same thing that happened when I switched the wires on the motor side- both front and rear switches would work the opposite of what they do now (and still opposite one another).

Maybe the hope is in trading pins 7 and 8 on the front switch (marked 62a)?

ja17

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Re: W108 Electric Rear Window
« Reply #11 on: May 09, 2023, 14:20:13 »
How about just rotating the switch on the door 180 degrees?
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback