Mysterious switch on '82 500SEL
 

Hi,

A friend of mine has a Lorinser 500SEL from 1982. Really nice car. It has the european AC system.
There's a mysterious switch that seemingly does nothing.
The decal on it is gone. The number on the side is gone except the lower number "(Lk) 03 8125 34". The female plug is 09967602 which shows up on eBay as a window defroster switch plug. But wiring is way different...there's a thick red and red/black wire, then another red wire from 3rd pin to 1st.
The pin layout on the switch itself is identical to a sunroof switch. There's also a thin black wire on the top of the switch not connected to anything.
When you press it, you can hear a crack through the speakers.

Does anyone have any clue what it may be?

Pictures: https://imgur.com/a/iQlQQuB

Thanks

Is it to raise or lower the antenna? There is no radio, so I would assume it's not working.

No idea. It doesn't affect the antenna.
All I've found is similar switches with numbers ending 30, 31, 36 were sunroof switches. This car has no sunroof.

Some Euro's had a high and low tone for the horn. That is where it was located but I wouldn't expect it to be that worn???

It doesn't stay in either position, it defaults to the center position. So not horn...because it doesn't affect it either.

Given the speakers crack when this sw is cycled, something that draws a reasonable amount of current is being turned on / off.

A thin wire makes me think there is an indicator bulb in the sw.

Does the wiring look factory and does it enter a main harness or is it an overlay.

I tried the pics but I've always had difficulty getting imgur to load as ti seems to want to load all pics at once, can you post single pics?

It would appear the vehicle has an electrically heated front windscreen. Used sparingly with the climate control defroster.

https://www.benzworld.org/forums/attachments/w126-s-se-sec-sel-sd/347152d1292327245-climate-control-wood-trim-7-switches-f15b1b3e.jpg

https://mbworld.org/forums/new-s-class-w222/570132-how-enable-electrically-heated-windshield.html

The thin black "wire" is a fiber optic cable for switch lighting

I cannot add pictures here, I don't know why...
Direct links:
https://i.imgur.com/QJkxAVE.png
https://i.imgur.com/fSPduXd.jpg
https://i.imgur.com/kg23y6s.jpg

The heated front could be it...what should it look like on the windshield?
The wiring looks factory. Definitely era-correct wires with black rubber shield/sock on them.

If heated front windshield, it is likely the type that has fine wires embedded in the glass.

If you turned the sw on and left it on, bring a compass near the glass and see if it moves. Don't move the sw while the compass is near the glass as this might re imprint the compass.

Would MB leave a switch like that in a car without a sunroof from factory?

Mysterious switch on '82 500SEL
 

https://uploads.tapatalk-cdn.com/201...10396ee70f.jpg

Its a momentary switch but I have no idea what it operates from the pic.

Sliding roof switch. P/N should be 0008206310. Here's one from an 85 W123 and the last number in the secondary part number is different, but the symbol is the same and it's a momentary switch. Now as to why this switch and wiring would be installed in a non-sunroof car...I have no idea.

https://www.ebay.com/itm/MERCEDES-1985-POWER-ROOF-SUNROOF-SWITCH-OEM-PN-000-820-63-10/192929535035?hash=item2ceb7f143b:g:LbUAAOSwHLNc6sfv

http://www.peachparts.com/shopforum/...1&d=1562027919

http://www.peachparts.com/shopforum/...1&d=1562027965