When you click the APPROACH button, and assuming the NAV 1 radio is tuned to the ILS frequency, it will control your left to right (localizer), and the altittude (glideslope). But not all ILS approaches have a glideslope, in which case you would click the REV, or BACKCOURSE button, with a backcourse approach you will have a localizer, but not a glideslope, so you will have to control your altittude manually.........
