GM Service Manual Online
For 1990-2009 cars only

The aim of your vehicle's headlamps can be adjusted by using aim tips located on the outer surface of the lens. The aim has been pre-set at the factory and should need no further adjustment.

If your vehicle is damaged in an accident, the headlamp aim may be affected. Aim adjustment to the low beam may be necessary if it is difficult to see lane markers (for horizontal aim), or if oncoming drivers flash their high beams at you (for vertical aim). If you believe your headlamps need to be re-aimed, it is recommended that you take your vehicle to the dealer for assistance.