Does your Volvo's XC90 tailgate feel way heavier than it should? Will it no longer stay open on its own. If so chances are that one of the gas struts has failed. You can replace these in pairs but it is usually just one that fails. Why pay the dealer hundreds of dollars for a 10 minute job you can do yourself for under 30 dollars. You can purchase these for under 30 dollars to your door from here: XC90 Tailgate Struts

Before you start make sure to support the tailgate. A better solution is to have a helper as the tailgate of the XC90 is very heavy. Whatever method you use, be sure to use caution and common sense. This is supposed to cost you 30 dollars not an arm or a leg.

Use a small flathead screwdriver and insert on the "backside" of where it inserts into "ball" (part of the hatch itself). There is a retaining clip that pops back. Once this is removed, then the strut pulls off the ball. It seems to be pressure fit.

Repeat the previous steps for the other side of the strut now. I didn't take the clip completely off the new unit, but rather, "lifted" it back with the same flathead, then it magically (well not exactly) popped onto the metal ball.

Thats all there is to it. Arn't you glad you didn't pay the dealer for this. If you still need more help, you can see the discussion topic for this repair here: XC90 Tailgate Strut Replacement.