Toshiba Satellite X200; Satellite X205 Maintenance Manual page 101

3 Tests and Diagnostics
NOTE: The "Fn" key cannot be tested in the keyboard test. To determine whether the "Fn"
key is working correctly, press "Fn+F6 " or "Fn+F7 " keys to check if LCD display
brightness change gradually.
SatelliteX200 / X205 /
Series Maintenance Manual 3-16