The Nissan door mirror is not only a cosmetic component on your vehicle, but as safety device it must by law be present on your vehicle at all times. Since the mirror glass of the door mirror cannot fail on its own, damage to it can only occur if it is a victim of vandalism or an accident. The other reason for a door mirror to be in need of replacing is if the electrical components of the mirror that adjusts the pitch and angle of it are no longer functioning. The electric motor that adjusts the pitch and angle of your Nissan door mirror will fail in time since it is an electrical component. When this occurs the entire door mirror assembly will have to be removed and replaced. This is not a difficult procedure but will require the partial disassembling of the door panel that the mirror is mounted to on your Nissan's door. The first step in the replacement procedure is to place the window glass in the upper most position. Then the battery has to be disconnected so the threat of an electrical shock or short is eliminated for the person working on your Nissan. With the electrical connections disconnected, the mounting bolts that hold the door mirror in place can then be removed. Be sure to either brace the mirror in position or have another person holding it so it will not topple down the door damaging the finish of your vehicle. When mounting the new mirror be sure to include the polymer or foam pad that will help seal the joint at the base of the mirror and the door itself. This will not only protect the finish of your Nissan but also prevent moisture from entering the door panel cause an electrical short.