The diagnosis of failing liftgate glass support struts is simple. A technician will inspect the way the glass opens and closes. If the glass does not stay open, or if it is too easy to close, the struts will need to be replaced.

To replace the liftgate glass support struts, a technician will lift the glass and hold it open it with a rod so that it does not fall when the struts are removed. The ends of the struts are fastened to the inside of the liftgate frame adjacent to the glass panel with a ball and socket joint that allows the strut to pivot. On most vehicles, the ball remains on the liftgate frame and the strut is removed when the technician manipulates a spring clip that retains the ball in the socket. On some vehicles, however, the ball remains in its socket and is unscrewed from the liftgate. The same procedure is followed on the glass side of the strut. With the old strut removed, the new one is installed in its place.

Both support struts on a panel usually wear out at the same pace. RepairPal recommends that they be replaced as a pair. If the combined force of the struts is not enough to support the glass (or other panel), the symptoms will simply diminish, not go away. Excess stress is put on the new strut when only one is replaced. And if one strut is stronger than the other, they will apply a twisting force on the panel causing misalignment and possibly damage. Also, the replacement struts should be OEM quality since they are specific to their application.

Any body panel that uses support struts - hood, deck lid, liftgate, or liftgate glass - relies on the proper amount of combined and equal force from both struts. If the force is not sufficient or equal between them, the panel will not open and close properly and can cause damage to the vehicle. Moreover, when the struts go bad, they may hold up the panel momentarily and let it fall when someone is underneath. Failing (or improper) struts can cause severe injury to the head, neck, and hands.

An intermediate DIYer can replace the liftgate glass support struts with little problem as long as the glass is supported properly. Care should be taken when manipulating the spring clips that hold the ball in the socket. They do not need to be removed from the strut, yet many novices lose the clips. Care should also be exercised when first closing the glass to make sure the tension is even and the glass is aligned properly.