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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Cosmetic and Lighting Modifications (exterior/interior) > Rear Fog Lights Information



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      01-09-2013, 07:11 PM   #1
jwzimm
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Rear Fog Lights Information

Hey Everyone,

I recently picked up an old euro light switch from a member here. It is one of the old ones that doesn't have the "Auto" position or the chrome knob. I had previously modified my OEM switch to enable the fogs by trimming the tabs on the dead button but I wanted to have the proper icon on the button and have it light up. I was expecting I could just swap the rear fog button over to my switch and it would be golden. Instead I discovered that the OEM switch circuit board did not have the LED soldered on though. After comparing the board from my switch (2011 with Auto etc...) to the one I picked up (no auto, 3 position switch) I noticed that the boards were identical except for the rear fog LED!! The old one had a four position pot on it and the part numbers on the boards were the same.

I decided to try out the board out of the old switch in my switch housing with the rear fog button installed in it and, lo and behold, it worked!! I now have a four position switch with the chrome knob and a fully functional rear fog button.

What does this mean for the community? Well, if you want to change over your OEM switch to have rear fogs you can pick up any euro switch! All you need to do is tear down both switches and transfer over the board, button, and lego piece (if yours didn't have one).

See the pictures below:
1. Old switch I bought and gutted
2. P/N of the old switch
3. Board out of my 2011 switch showing no rear fog LED
4. Switch pot on my 2011 board. The old board was EXACTLY the same.
5. P/N on my 2011 board. Again, the exact same as the old one.
6. Two extra "lego" pieces. Let me know if you would like one.
7. OEM switch with the fog button in
8. OEM switch showing backlight works (PITA to take that photo)
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      01-10-2013, 03:10 PM   #2
jwzimm
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I did notice something today however. The little light on the left side that would come on when the auto headlights were on is not working. I expect that the LED for that light isn't on the board I put in. I am thinking I may try and solder it over from my old board to get it working. It isn't a huge deal though, it was really just an idiot light.
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      01-10-2013, 07:27 PM   #3
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Not that anyone seems to be paying attention but I wil give an update anyways.

I found that, indeed, the idiot light LED was missing. I swiped it from my old board and soldered it on. Tested it out and....no dice.

Turns out there are also little "control chips" on the board that feed each LED. I found the one that controlled the idiot LED though and swapped it over too. It worked!!! I now have a fully functional LCI light switch with a rear fog button!

Photos below:
1. Location of the idiot LED
2. Location of the idiot LED control chip. Similar to the ones next to it.
3. Locations of the rear fog LED and control chip (wasn't present on this board as it is the OEM one from my car).
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      01-10-2013, 07:53 PM   #4
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This is some nice information thanks for the write up. I'm sticking with my USA spec unmarked rear fog light switch haha
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      09-12-2013, 07:42 PM   #5
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Good info. I ran into the same problem as you except the person that sold me the euro switch neglected to tell me that it didn't have the auto position. I ended up using my own board since I wanted to keep the auto light.

I'm assuming I can do the reverse of what you did and swipe the rear fog LED and control chip and solder it onto my own?
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      09-12-2013, 11:15 PM   #6
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Quote:
Originally Posted by bimmertt View Post
Good info. I ran into the same problem as you except the person that sold me the euro switch neglected to tell me that it didn't have the auto position. I ended up using my own board since I wanted to keep the auto light.

I'm assuming I can do the reverse of what you did and swipe the rear fog LED and control chip and solder it onto my own?
Absolutely! That is why I included that last photo showing where the rear fog LED and chip are. Be gentle with the soldering iron and you should be golden.

Oh and the polarity of the LED is important. Just be sure to get the components oriented correctly when you transfer them
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