On my pro106 when I program a TG there is a backlight setting for which ever department you program,
just scroll down the list to backlight use the right arrow to say YES & hit SAVE . See below
Backlight: Sets how the backlight will function while the ID is active. Default is Off.
Press or to select Off, On, or Flash.
Note: Does not function when Light Mode (in the GLOB menu) is set to Stlth. Light Mode has to be set to Norml, Key, or Ignre for the backlight to come on only during a transmission