Many thanks to MBDoc and Super Turtle, I think i'm on the right path.
Super Turtle, main reason why I'm so eager over this relay is: I have read that it controls the fuel system as well as idle control, of which both I'm experiencing some minor hitches. I hope that by replacing this relay, it would be a first (and hopefully, positive) step towards smoothening out the idle and fuel delivery. My 280SEL is a 1983 car, and I suppose there're some wear-and-tear items to replace.
The only problem is, I am not exactly very sure if my car has this relay. I have gotten conflicting opinions, both from this forum as well as from different mechanics here.
If there is one, I would like to replace it.
I'm still trying to find out, and I appreciate all your help, thanks!