Your GMC Sierra is known for being rugged and safe, but a malfunctioning signal lights is a hazard on the road to both you and other drivers. Because of this, you should replace the signal lights whenever they crack or burn out.
Set your Sierra's parking brake and remove the keys out of the ignition before starting.
Walk to the back of your truck and lower the tailgate.
Remove the two screws from the side of the taillight assembly. Put the screws in your pocket or in a small bag so you can find them later.
Disengage the taillight assembly from the truck by pulling it rearward.
Press the bulb socket release tab, and twist the socket counterclockwise to remove it from the taillight assembly.
Lift the old bulb straight out of the socket and replace it with the new one. Then, twist the bulb socket back into the taillight assembly until it clicks.
Activate your Sierra's new turn signal. If it lights up, screw the assembly back into place and close the tailgate.
