Electrical switches in the door latches can fail, causing the door locks to rapidly actuate up and down multiple times when the locks are activated by either the keyless remote or door lock switch. A new door latch will need to be installed.Google+
Car Problem Reports
Mercedes-Benz ML55 AMG Electrical switches in door latches may fail
Mercedes-Benz ML55 AMG Problem
Average Mileage: 107,766 mi (80,000 mi - 124,000 mi)
Left rear passenger door shotguns when closing, will not lock, over $ 500+ for dealer to repair, we live with problem simply manually push lock down, it stays down , stills makes noise when trying to lock, not worth $ 500 to fix
Visitor, 2000 Mercedes-Benz ML55 AMG, 119,300 mi
Driver side door mechanism switch failed causing erratic behavior of all locks.