To Neil and Beachdog2001:  Both of you have experience, but I haven't tried the FMC autotune to the ILS frequency and heading, still in the habit of manually tuning the ILS.  How close to the localizer and TDZ do you have to be for it to autotune?  I normally approach the localizer at 45 degrees from the localizer heading.  Does the autotune sense the localizer while converging on it, and then if LOC is selected will it turn the aircraft onto the localizer course?  Last question:  where there are parallel runways and localizers (e.g. KSFO, KMIA, KATL) does the autotune dial in the closer of the 2 (or more in the case of ATL) localizers?  If you cross the first localizer will it then retune to the frequency and heading of the second?