w203 steering wheel swap

[Requin]

Hello MB fans and owners.
A long time ago I bought a 2001, c180, 2L petrol, w203/
After it stood neglected for years I decided to start work on it.
Replaced a ton of parts, paint job on the way, the works.
I also got a 3 spoke steering wheel and while the airbag connectors fit, the horn and buttons connector will not.
The connector from my car has 4 wires/pins and the new steering wheel has a 3 pin connector.
Anyone know how to merge those wires, in order to make the buttons and horn work?
Here's a photo of the whole deal.
The upper is of my original connector/wires and the lower photo is of the new steering wheel connector/wires.
Thanks.

 

[whitenemesis]

The communication protocols are different with the 4 and 3 spoke wheels.
I changed from the 3 to the 4 and had no end of problems until we discovered there had to be a conversion box in the steering wheel. Even MB didn't realise this.

Not sure how one can go 4 to 3 though.

 

[Requin]

Conversion box? What does it exactly do? Do you have a photo or a part number?
If there is one for the 3 to 4, there must be one for the 4 to 3. I guess...
I have seen the mod on other 2001 c class cars but I have no clue how they managed it.
It can't be to hard, 3 wires must merge with 4... I just do not know how.
P.S I only want horn and menu buttons. Phone and audio are of no use to me.
Thank you.

 

[whitenemesis]

This is the thread, there's a link to the original swap attempt in the first post

http://www.mbclub.co.uk/forums/interior/54716-birds-eye-maple-steering-wheel.html

 

[Requin]

Read it top to bottom but it does not help.
Thank you for the time and link.
If anything else comes to mind, let me know.