Trunk ajar light won't go away

[BSchul77]

I have a friend who has this same issue on his. Except his issue stems from the trunk plastic liner that goes around the back of the trunk, behind the taillights, is missing from his car. So when the trunk is shut, that boot doesn't have anything to push against, to tell the car that it is shut. So your issue as you have found out is from the plunger/boot. That plunger isn't detecting that your trunk is shut because it is not working, so it's sending a signal as if the trunk is open. Hence the light being on in the trunk, and on the dash.