GMC 2001 Sonoma Owner's Manual page 304

Headlamps
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One Piece Composite Headlamp System
1. Open the hood.
2. Remove the black retainer clips by lifting up.
3. Pull the headlamp assembly out.
4. Unplug the electrical connector.
5. Turn the bulb assembly counterclockwise to remove
it from the headlamp assembly.
6. Put the new bulb into the bulb assembly and reinstall
it in the headlamp assembly by turning it clockwise
until it is tight.
7. Plug in the electrical connector.
8. Put the headlamp assembly back into the vehicle.
Install the two retaining clips.
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