The electric trunk latch solenoid can get stuck in the open position making it so the trunk will not latch closed. The diagnosing technician should verify correct electrical connection at the solenoid and check for correct cable routing. The trunk latch most commonly will need to be replaced.
Trunk Will Not Latch Closed on Mercury Sable
Average mileage: 122,400 (57,000–240,000)
7 people reported this problem
2008 Mercury Sable 132,000 mi, Visitor
trunk latch not working. Had same problem on 2000 Taurus
2008 Mercury Sable 240,000 mi, Visitor
trunk makes loud noise when push switch to open and close
2003 Mercury Sable 58,000 mi, Visitor
Occasionally the trunk pops open. Not too often.