I am making this post because I tried searching about my steering wheel controls not working, and I didn't find much, Basically the controls on the left side of my steering wheel slowly began "not working", I read about other people having the same issue but the only "fix" was to call the dealership find out it costs alot to get fixed and that was about it.
Basically I found a thread that explained to me how to get that Steering wheel torn apart enough that I could do some investigating, I'll write up a "how-to" in this thread when I get home where I have pictures.
Big key, the connector attached to the PCB (printed circuit board) had broken away from the solder, with no solid connection in place the button malfunctioned altogether.
If you are having problems with this in your car I think this is one place to check, I just soldered mine back in and it works like a charm.
1. A brain.
2. Torx T30, one that will fit between your dash and the steering wheel and can reach in and unscrew the unit that holds the airbag to the steering wheel.
3. Torx T06 (let me double check on that when I get home) to take the control unit apart to get at the connector.
4. Soldering Iron with a fine point and some solder.
* NOTE: I disconnected my battery just to be safe, I recommend the same for anyone else doing this "mod"
1. Remove the airbag unit. Follow the directions located here:
W203 steering-wheel swap how-to
2. Once you have the Airbag/Steering wheel controls unit separated, place the unit facedown on a soft rag (dont want scuffs of course)!
remove the 4 screws (see attached)
3. Between the metal plate in step 2 and the rest of the unit is this piece, remember how you took it out, here it is:
4. Next remove the appropriate steering wheel control from the unit see they are attached by a couple screws in the locations highlighted.
5. The rest of things are detailed in the next picture, but the long and short of it is this,
a. remove the screws holding the unit together
b. pull the circuit board out
c. if you can't tell if it is connected good or not, if you can wiggle it that's
not a good sign
d. I decided to hold the connector on (after I accidentally finished it off)
then heat up the solder on each end and let it cool so it stays on it's
own make sure you do a good job soldering it in, I'm not teaching
soldering in this tutorial. Plus you don't want to have to take it apart
and do it all again.
6. Once it's all finished and you've ohm checked it (checked for continuity a.k.a. no shorts, opens etc) put everything back together in the reverse order you took it apart.
7. Good luck and have fun,
If anyone needs more details or better explanations please let me know, this is really one of the first tutorials i have written and hope it's understandable.
Thank you to Bif Powell from mbworld.org forums, for the info on how to get the stuff apart.
*Note sorry at least one pic is not very clear, I had poor lighting.