How to change the rear wiper on your 2009 Mercedes-Benz GL450
Release the old blade
Lift the wiper arm off the window. On many vehicles the wiper arm will not come very far off the window. Grasp the wiper arm with one hand and rotate the blade directly toward you.
Remove the wiper
Once rotated, the wiper will release from the wiper arm with a gentle click. You can now take it off the arm.
Position the new blade
Place the small bar attachment on the new wiper blade into the hook on the wiper arm.
Lock the blade into place
Rotate the blade away from you and into position. Once it’s oriented correctly, pinch the new blade against the wiper arm. It will snap into place.
Your wiper has been installed. Gently rest the wiper back against the rear window.