Locking system. i have had my truck in several times over this issue. they have cleaned and replaced connections. they also replaced the door lock and wiring harness and 3 years later i can not drive my truck and leave it . it will not stay locked. the service dept. either looks at it and doesn't note it on the service records or just ignores my request. i have even had on state.... the problem could be an airplane or garage door opener.. ha. i paid for a high end truck and for a year or better i can't drive it anywhere. even setting in my driveway .. the locks go up and down.. some times one door will lock and not all and others i use the tail gate at all. it won't open. i am very upset over this whole issue and the way the service dept has blown me off. *jb