Cruise not working?

[gmcracing92]

i just recently bought a 99 chevy pickup. i came to use the cruise and it doesnt work. when you push it over to "on" , the green light doesnt come on in the dash. nothing happens, but when i listen carefully, if i move it from off to on i can here a clicking sound momentarily from the little box on the firewall. i already checked the fuse and its good and if it makes a noise when i move the cruise to on, that must mean that the cruise/blinker thing is good right? so could it be in that box on the firewall, can someone tell me what its actuall name is and what i would expect to pay for a new one? thanks