GM Service Manual Online
For 1990-2009 cars only

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, we recommend that you take your vehicle to the dealer for service. However, it is possible for you to re-aim your headlamps by following the procedure in the service manual for your vehicle.