Did it run under Mavericks or whatever the previous system was as you have not told us. If so, go to System Preferences > Printers & Scanners > Print and select the printer in the left hand pane and hit the little (-) button. If locked you may have to unlock using your admin password.
Then hit the little (+) button and see if it is found when connected and powered up.
There doesn't seem to be any Yosemite supported scanning software for that Xerox Phaser 6180mfp at this time.
Neither from Xerox or even VueScan. But I guess you already knew that.
Are there any older drivers left you could try with Image Capture if you just installed Yosemite over your previous OS X version. Sometimes it just might work, but Yosemite seems to be fussier than most OS X versions.