Access control device for disposition in or on a motor vehicle, comprising a control circuit and a communication circuit coupled thereto, having an electric actuator which is coupled to an actuating section, the actuating section being designed for coupling to a vehicle-side mechanical blocking means of an opening lock, the electric actuator driving the actuating section under the control of the control circuit in order to change a blocking operation of the blocking means, having a first supply interface for coupling the access control device to the voltage supply of an on-board power system of a vehicle, wherein the access control device has a second supply interface for supplying voltage from an external voltage source, the second supply interface being coupled at least to the control circuit, the communications circuit and the electric actuator wherein the control circuit monitors the second supply interface for voltage applied thereto and is configured to drive the communication circuit in dependence on detected voltage values at the second supply interface to initiate data communication, the control circuit being designed, as a function of data transmitted in the data communication, to activate the electric actuator for moving the actuating section in order to cancel the blocking operation of the blocking means characterized in that a vehicle door handle is formed in which the control circuit, the communication circuit, the electric actuator and the second supply interface are accommodated, and wherein the electric actuator is accommodated in the vehicle door handle and is placed in its installation space as a substitute for a mechanical lock cylinder. having an electric actuator which is coupled to an actuating section, the actuating section being designed for coupling to a vehicle-side mechanical blocking means of an opening lock, the electric actuator driving the actuating section under the control of the control circuit in order to change a blocking operation of the blocking means, having a first supply interface for coupling the access control device to the voltage supply of an on-board power system of a vehicle, wherein the access control device has a second supply interface for supplying voltage from an external voltage source, the second supply interface being coupled at least to the control circuit, the communications circuit and the electric actuator wherein the control circuit monitors the second supply interface for voltage applied thereto and is configured to drive the communication circuit in dependence on detected voltage values at the second supply interface to initiate data communication, the control circuit being designed, as a function of data transmitted in the data communication, to activate the electric actuator for moving the actuating section in order to cancel the blocking operation of the blocking means characterized in that a vehicle door handle is formed in which the control circuit, the communication circuit, the electric actuator and the second supply interface are accommodated, and wherein the electric actuator is accommodated in the vehicle door handle and is placed in its installation space as a substitute for a mechanical lock cylinder.