The front bumper of your GMC Sierra is held in place by two plastic clips in addition the several securing bolts along the top and bottom of the bumper. If these clips break, they need to be replaced. Although the clips are not the essential fasteners of the bumper, they are necessary. Replacement clips can be purchased online or through your local Chevrolet dealer. Installing the new clips is fairly simple. The installation process takes about thirty minutes.
Park your Sierra on a flat surface and engage the truck's parking brake.
Crawl underneath the front of the vehicle and use a slotted screwdriver to pry out the clip underneath the left-side headlamp assembly. Remove the clip under the right-side headlamp assembly as well. If the clip is broken, you can use glue to repair it, but the best solution would be to replace it.
Attach the replacement clips underneath the headlamp assemblies. Wiggle the bumper to make sure it is secure.
