instrument cluster golf mk1

Hy guys,

What actually this switch do?
 

It's for the MFA trip computer.

You have two memories so you can for example have position 1 just for a single trip if you like and you pull the knob to reset it to zero when you like, and if for example you move to position 2 you could keep that as a long term view of mileage, average speed, mpg etc.

Thanks, a lot,
i cant check it because my mfa display or button does not work,  

There is also little arow showing fuel consumption. mines sometimes appears but yust at the end. From which engine part he takes reading ? I want to check all the connections, or maybe my mixture is not setted right.
 

That should only work in 5th gear, basically works on vacuum from the inlet manifold,  but it connects to a "thingy"  first.  Afraid I no longer have one to show a photo.

You right its appear on 5th gear. I wondered why vacum goes to dashboard now its clear. Thanks. Maybe you remember what the reading showed yours?

i checked and reconected this vacuum to inlet manifold, and its started to work properly. Happy,

But somehow i broken that little connection, is it possible to buy it all brand new brake booster pipe?  it looks like in photo,