2005 Buick Rainier Liftgates

You should remove the door trim panel, the front half of the water deflector to expose the door access hole, the bolt retaining the front lower window run channel, the 2 bolts that retain the check link to the pillar, the rubber dust boot from the check link to gain access to the door retaining nuts, the 2 check link retaining nuts from the door and the check link assembly through the door access hole.

You should remove all of the related panels and components and the sealer surrounding the hinge, scribe the location of the hinge, hand-sand the existing hinge with 100 grit sandpaper to locate the four weld locations, center punch each weld location, drill a 3 mm (1/8 in) pilot hole, drill through the hinge base using a 19 mm (3/4 in) rota broach hole saw or equivalent, use a chisel to separate the hinge from the mating surface and remove the hinge and the remaining weld from the mating surface to ensure a flush fit of the service hinge.

Water from a car wash or off the road may have entered the latch and frozen and this causes the detent to move slowly. You should verify that the striker properly engages the latch and that no obstructions are preventing the door from closing, allow the latch to completely thaw, and apply compressed air for two seconds to the latch to force out any moisture.