Hello guys I lucked up on a full functional comand head unit from a junkyard for only $12. Hell of a deal I would say!!!

The problem I'm having I can't get my steering wheel to control the unit. The unit came out of a fully loaded facelift Eclass. I have it installed in a 02 clk

I've hooked up everything but the gps, cd charger and Vss wire. And im not sure if the vss has something do with it not working right or if it's my original radio harness that's not configure for a comand unit.

All I want from this comand unit is its
Good looks in dash
Steering wheel controls
Aux input

I don't care about the gps its out dated anyway

So my question are

1. How can I get the steering wheel to control my comand?

2. What's is the vss wire for and is it necessary ?

3. Is this something the dealer has to program or should this be plug and play?

Thanks for reading