Depending on the year of manufacture, the mounting points may differ.
Front bumper
-open the hood.
-(if there is) under the hood pull out six pistons and remove the cover plate over the radiator grille.
-under the cover, release two pistons (you need to rotate 90 degrees) and Unscrew one screw that attaches the top of the radiator grille.
-release the retainers in the fenders under the headlights (you need to pry with a flat screwdriver)and remove the radiator grille.
-in the gap between the headlights, we Unscrew two screws on each side (twisted from top to bottom), which attach the bumper brackets to the body.
-(if any) in the wheel arches, Unscrew the screws that attach the undercarriage (front part).
-from the bottom side, we Unscrew one screw on each side, which attaches the sides of the bumper to the brackets.
-remove the connectors from the fog lights.
-with an assistant, we pull the bumper forward.
Rear bumper
-pull out the license plate lights and remove the connectors.
-from the bottom side, we Unscrew two nuts and two screws on each side, which attach the bumper brackets to the frame.
-Unscrew the four screws (screwed from the bottom up) that secure the lower part.
-with an assistant, we pull the bumper back.
How to remove front and rear bumper GMC Yukon (2007-2014)