It should light whatever it can reach. You can tweak with those setting upping them and such to make them illuminate and glow more.
I've seen the iron Giant before and I don't know if you're going totally like the original or what but his eyes didn't light too much just enough so that they could be seen in the dark. But you could be going for something different! Anyways hope this helped even if not for this model! Later
May the force be with you...always!
A Jedi shall not know anger nor hatred nor Love
The only way to live a good life is to act upon your emotions
A warrior is reborn when he has something to protect