Why wont door ajar light go off what can cause problem on my 2002 Ford explorer

One of the vehicle doors is seen to be open. If all doors are shut tightly, a diagnostic tool will be needed to determine what door is showing open even though it's closed. A latch replacement may be needed, or lubrication of the latch to free up a possible binding switch internal to the latch on the affected door may be needed. www.repairpal.com/repair-shops