Abstract: A system for unlocking a key cylinderless automobile vehicle door includes a portable object having an identifier and a circuit for interrogating the object. The circuit powers the object and interrogates the object when it is outside the vehicle. The interrogating circuit supplies a signal authorizing unlocking of the door as a function of the identifier. A standby power supply, which is separate from the main power supply of the vehicle, also powers the circuit and the object. As a result, the vehicle door does not require a key cylinder while still ensuring unlocking even if the main power supply of the vehicle fails.