This problem is on a 453, but I imagine the mechanism that triggers the warning is the same on older models. Has anyone else had this problem? Does anyone have a link to an electrical diagram or parts schematic that shows how the door open sensor for the trunk works?
Try spraying so WD-40 or some type of lube in the mechanism... ...close the glass and pop it with the button by your left knee. Fully lock the ride with the FOB and hit the trunk button. That seems to do the trick!