LED Window switch (aka Window switch illumination repair)

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mvrolix

New member
Writing this article in English for wider distribution.
I bought a new project recently and almost every swich remained dark when you turn the key or switch-on the lights. So also my window switches (both) had an issue with the little light in them. I checked the fuse, but because the dashlight would come on, I already suspected the switch itself. The usual common response from Google is to replace the entire switch because the lamp is internally soldered. 1992 was the year where "some" illumination would be done with LED's but overall in most was done with traditional light bulbs.
Foto1 - old lightbulb.jpgFoto2 - old light bulb and switch.jpg
I removed the switch from the console and opened them carefully to find indeed that there is a traditional lightbulb in it. I had purchased in the past some LED's from Ali Express that run on 12 Volt and give this nice amber color to match that famous typical BMW-Orange on the dash.

Foto3 - LED with wires.jpgFoto4 - LED removed from wires.jpg
I have used these already to have Ambient Light in the footwell area and the ashtrays so I will be using these here too. This switch is a 1992 Car that uses the older style Window lifters with the electronics in the doors instead of the later models with the Ground Module. I have not checked or compared the Pin layout but on mine, the swithch uses Pin 6 for 12Volt (Grey/red) and Pin 5 is ground (Brown) for the light in the switch (important for te polarity of the LED). I desoldered the traditional lightbulb and removed the whte litthe plastic bracket as I need some more room for the LED and it's resistor.
These LED's have long red and black wires that I removed. I just keep the blank wire and a little piece of the connector to the resistor as shown on the image. I soldered this one in (resistor on Pin 6 and ground to Pin 5) - exactly where the original lightbulb was soldered. Just make sure that you respect the polarity of the LED.
Foto5 - LED soldered in.jpg
Did a simple test and added a little bit of hot-glue to keep the resistor and LED in place and re-assemled the switch as seen on the image below. You cannot assemble it wrong. these German engineers made it complete fool-proof so that it fits only in one way.
Foto6 - switch assembly1of4.jpgFoto7 - switch assembly2of4.jpgFoto8 - switch assembly3of4.jpgFoto9 - switch assembly4of4.jpg

With the result at the end: 2 light switches are visible again in the dark and because they are LED's they will not fail anymore in the future.

Foto10 - switch remounted.jpg
 
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