How do you replace a headlight bulb on a 2001 GMC Sonoma?

No tools required. Raise the hood. On the backside of the core support there will be two plastic strips behind each headlamp assembly. Pull upward on the strips for the affected assembly. When they disengage, pull slightly upward and outward on the assembly. Unplug wiring as desired and replace bulbs or the entire assembly. Headlight bulbs are 9005 and 9006's. To reinstall engage the lower tabs of the assembly in the slots in the core support, then push the two prongs through the square hole. Reinstall the strips and close the hood.