KEYLESS ENTRY Jeep Grand Cherokee's security system includes a Sentry Key immobiliser that makes it almost impossible to start the vehicle without the owner's key. The vehicle theft security system also monitors the liftgate window switch and liftgate lock sensor. It keeps track of door ajar switches, ignition circuit, power lock circuits and the hood switch. If any of these monitored areas are triggered, Grand Cherokee will blow the horn and flash indicator lamps intermittently.