GMC 2006 Sierra - Manual (Page 478)

Roof Marker Lamps
To replace a roof marker lamp bulb, do the following:
1. Remove the
two screws and
lift off the lens.
2. Install a new bulb into
the socket and turn
clockwise until it locks
into place.
3. Reinstall the lens and tighten the screws.
To replace a center roof marker lamp bulb, do the
following:
1. Remove the six screws from the center roof marker
lamp assembly.
2. Turn the old bulb counterclockwise to remove it
from the socket.
3. Reinstall the lens and tighten the screws.
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