did you take it apart?? if not then take off your dash, and get a tiny screw driver in the back of the bulb and turn it so it pops out. when its out it should have a little blue cover over it which give your head light switch that hyper white kinda color. i dont know if you can take the bulb out of the stick its on but if you could then you could go to superbrightleds.com and get T1.5 instrument bulb. its the same bulb as your hvac knob light up panel and your turn signal and high beam lights. youd prolly be better off goin to a gm dealer and getting a new light.
hope this info helped ya out some.