Please help identify this key-like button in a 1981 Mercedes 240D
 

Dear friends,

I'm not familiar with diesel cars. I would like to know the name
and purpose of the key-like button (with the label Adecco attached to it) as shown in the attached image of a 1981 Mercedes 240D.

Thank you very much for your precious help.

Best regards,


Eric

Eric:
That's the idle adjustment. Mostly useful for cold weather starting.

It doesn't help for STARTING, it simply allows you to run at a fast idle while the engine is cold.

Have a great day,

what button is for
 

it is to put your diesel in mach one so you can pass all those
porsche's and ferrari's haa haa:D