GMC 2006 Sierra - Manual (Page 477)

To replace a front turn signal, sidemarker or DRL bulb,
do the following:
1. Open the hood. See Hood Release on page 5-13
for more information.
2. Remove the headlamp assembly as described
previously. See Headlamps on page 5-63 for
more information.
3. Press the retainer clip (B), located behind the turn
signal assembly, towards the outside of the vehicle.
4. Pull the turn signal assembly out of the vehicle.
5. Press the locking release lever, turn the bulb socket
counterclockwise and remove it from the turn signal
assembly.
6. Remove the old bulb from the bulb socket.
7. Install a new bulb into the bulb socket.
8. Insert the bulb socket into the turn signal assembly
and turn it clockwise until it locks.
9. Reinstall the turn signal assembly back into the
vehicle placing the hook and posts on the inner side
into the alignment holes first, then the outer side into
the retainer bracket until you hear a click.
10. Reinstall the headlamp assembly.
5-65