what is it? and how do i do it?

hey everyone... i need someone with a little expertice. i want to know what this thing is... its a little black rectangular box about 10cm long 4 wide and it looks like it has a series of prongs for connections on it about 12 or so. it was making a clicking noise when the car was off like a bad relay or something. its placed inside the drivers right hand side foot panel area. if you sat in the drivers seat its about knee hight. does anyone know what it is and why it would be making a clicking noise? please help me on this one.

and also does anyone know how to reset the computer from economy to proformance ive serviced it myself but dont have the connection to reset it so the service lights go back to normal.

i have a 1987 525e (e28) bmw if that helps any?

thanks heaps!!!