Chevrolet 2004 Express Van Owner's Manual page 304

8. Without removing the headlamp assembly itself,
remove the bulb socket from the back of the
headlamp on the driver's side.
9. Turn the bulb counterclockwise one quarter turn to
remove it from the socket.
10. On the passenger's side, turn the bulb clockwise
one turn. Do not touch the glass part of the bulb.
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11. Install the new bulb into the socket and return it to
the headlamp assembly.
12. Put the headlamp assembly back into the vehicle
and reinstall the two pins.