A method is provided of controlling a combination of a tractor (10) and a baler (12) coupled to the tractor (10). The tractor (10) includes rear wheels (22) driven by an engine which is coupled to the rear wheels (22) by a transmission, an operator movable command device and a tractor control unit operable to control tractor motion in response to operation of the command device. The baler (12) includes a baler system (113) for receiving crop, for baling crop into a bale and for ejecting a bale from the baler (12), and a baler control unit (162) coupled to the baler system (113) and to the tractor control unit. The baler control unit (162) generates a tractor halt signal in response to a request of the baler system (113) and the tractor control unit preventing tractor motion in response to the tractor halt signal. When the tractor halt signal is generated, the baler control unit (162) enabling motion of the tractor (10) if the operator issues a command for the tractor (10) to move by manipulating the command device, and within a predetermined time period of said command being issued, the baler control unit (162) generates a tractor motion enabling signal in response to a current operating condition of the baler system (113).
