OBC Button Lighting

 

Disclaimer:

This is a description of what I did to modify the color of my OBC buttons on my 1998 BMW M3.  I recommend thinking through what you are doing very carefully before actually doing anything.  Take your time, and double check everything you do.  I won't be held responsible for anyone attempting this on their own.  You cut, drill, bend, burn, melt or break pieces of your car at your own risk. THE OBC IS NOT CHEAP!  IF YOU FUCK YOURS UP, I AM VERY SORRY BUT I WON'T BE HELD RESPONSIBLE!!

I am also assuming some basic knowledge of wiring and automotive modification.  I don't describe every step in minute detail.  If you don't know how to solder, stop here and get someone to help you.  If you don't know how to remove interior trim pieces, stop now and get someone to help you.

Introduction

Ok, I wanted a blue interior.  I like blue, plain and simple.  That BMW orange interior is just too blah for me.  I started with the sunroof switch because it was easy to get to, and I figured if I blew something up, that would be the cheapest component to blow up, and the least necessary (Its winter!  No need for sunroof!).  Please read that write up too, because it has some useful information.

Parts

I got my LEDs from http://www.eled.com.  I already had a soldering iron and solder, but both are cheap from Radio Shack.

3 -  3mm, 200 mcd, 5 V, 20 mA 468 nm blue LED part no. E7104PBT

Basically, the stock orange LEDs are replaced with an LED color of your choice.  This example is blue.   I recommend using the right size, which may be found at http://www.eled.com.  I believe the 3mm is the correct size.  You are on your own as far as the electrical specs of these components.  I believe the stock ones to be 4 or 5 volts, 20-40 mA, 50-300 mcd, but these are just estimates.  In this specific example, a 5V, 30 mA, 200 mcd blue 3mm LED was used.  

The wider the viewing angle is, the better.  Mine were only 20, and there are some areas of the buttons dimmer than others.  The light is cast from the LEDs and routed through some light transmitting plastic pieces.

There are yellow, blue, red, green, white, orange (duh!) LEDs available, and MAYBE even purple LEDs somewhere, I am looking.  Feel free to experiment.

Tools

Soldering iron
Pliers
Wire cutters
Small Flathead screwdriver

Procedure

Again, please take your time when making any permanent modifications.

Remove the OBC unit by pushing outward on it, accessing it from the access hole in the sunglass holder just beneath the OBC.

Remove the wiring harness.  Unscrew the 4 hex head screws holding the OBC together.  Remove the back cover.  The circuit boards are held in by plastic pieces that flex out of the way.  Poke around gently at the tabs that hold the circuit board in place, and pry it away from the circuit board.  This takes some delicate maneuvering, so be careful, but I figured it out pretty quickly without breaking anything.  I may post pics in the future.  Email me if you have questions.

Once you get the circuit boards out, take off the clear plastic optical reflector piece.  It is held by little prongs that latch on the black plastic piece.  Use a small screwdriver to unlatch all of these and then pull off the clear plastic.  The black plastic piece is similarly latched to the circuit board.  Take this off.  Be careful to pay attention to the gray rubber pieces and how they all go back together on the circuit board.  

You will have the following:

Unsolder the LEDs from the circuit board.  Mine was check control and temperature, so I only have 3 LEDs.  Full OBC probably has 4.  Very basic OBC may only have 2.  Your mileage may vary.

Each of the LED connection points has a small - sign indicating where negative is and where positive isn't.  The LEDs I got from eled and Radio Shack both had a longer + lead than the - lead.  Your mileage may vary.  You can usually use a small watch battery to compare the original orange LED leads to your LEDs if there is any question.  

Cut the LED leads to the same length as the stock ones.  Try not to bend the leads.  Insert the LED into the white plastic mount, maintaining proper orientation to negative and positive, and solder it in place.  Repeat for the remaining LEDs.  

Assembly is opposite of disassembly.

Feel free to inquire with questions or comments.  BWM@nolimit.to

Good luck!