Depends on the File and the application settings. Typically an application like Adobe Acrobat/Reader renders for RGB, so color is used to make black, also, they tend to print using all 4 colors to get a deeper darker black as well. So in most cases, the answer is yes, they use all 4 colors to make black. But....
Changing that isn't hard in most cases, simple File > Print > Advanced in acrobat/reader
Also, in the driver there may be a setting as well, but it depends on the driver type and model, in most cases, if it exists it would be under the Advanced tab Here is is in the Xerox PS driver (Version 3 type), these types of settings simply won't exist in a PCL driver though
