The angel eye (halo) rings are part of the "side lights" and come on when you turn the headlight switch to the 1st click to the right of OFF (along with all of the "park lights)...and stay on when the headlights are turned on (2 clicks from off).
So anytime the headlight switch is moved to a position that ANY of the lights will illuminate...the angel eyes will turn on.
Also, the 4.8is should have adaptive bi-xenon headlights...so if you move the headlight switch to the "AUTO" position (one click to the left of OFF)...then when the ambient lighting gets dark enough and the headlights turn on...the AEs should illuminate...or if you have the headlight switch in AUTO mode...if you were to press the fog light switch, the headlight "low beams" should turn on...thus the AEs should also illuminate in this scenario.
Do you have the check control warning illuminated that says "CHECK SIDELIGHTS"? If you do, then the angel eye bulb(s) is probably the reason the warning is on since you don't see them illuminated:
